The team
David Jonker
David Jonker (1974) facilitates, consults and coaches. He co-founded Unleash together with Coen Koomen.
David gained his corporate experience with leading companies in the international Food Sector. He discovered his passion for facilitation and coaching and is eager to empower individuals and groups to unlock their potential. David develops training programs focused on leadership, personal development, and change, always prioritizing a playful yet deepening approach. He works with individuals and groups at Schiphol Airport, Rabobank, Quooker, and Fairtrade, helping them navigate challenges and discover their talents.
David is a fast thinker and quick to act. With him around things move and shake, and his ability to create structure and organize brings confidence to those around him. His sense of humor and the twinkle in his eyes easily crosses cultural borders. His favorite movies include The Color Purple, Apollo Eleven, and Saturday Night Fever.
You want David on your team when a safe space for participants is required, followed by a free exploration of solutions and ideas.
Coen Koomen
Coen Koomen (1969) facilitates, consults and coaches. He co-founded Unleash together with David Jonker.
Coen started his career as marketeer and business developer at Grolsch Breweries and Caterpillar. During a two year global cycle tour he started working in a school in Nepal , resulting in an educational NGO, which ran for 5 years. He had so much fun doing this, that he never left the field of learning, developing and change since then. He's educated in Theory U at MIT (Boston) and in Constellations at Hellinger Institute (Copenhagen). Coen currently facilitates programs in the field of leadership, strategy and change for Fairtrade Int, Schiphol Airport, Rabobank, Quooker, TWD, Gemeente Rotterdam and many others.
He chooses his partners and clients well; trust, equality and a good sense of humor are crucial. He uses many playful and powerful methods to bring out the best in people and organizations. Coen loves: courageous leaders, nature retreats, wicked problems, creative solutions, contribution to society, personal deep dives, concrete action, dance all night on techno, outdoor theatre at Oerol and strong espresso. He believes every person and organization has the wings to fly and create something unique. His favourite movies to watch are: Captain Fantastic, Matrix, As it is in heaven and 12 angry men.
You want Coen on your team when you seek a breakthrough. The programs Coen designs become stories that generate enthusiasm among current and future participants.
Femke Ottevanger
Femke Ottevanger (1975) is facilitator, trainer and coach. She works as trainer/coach since 2000, of which many years for de Baak, as trainer of Young Executive Program and The Informal Leader. Femke is lead trainer for leadership programs at Mammoet, Post NL, Arriva, KPN, TWD, Connex and Rabobank.
Femke is a certified Haptonomist, (team)coach and intervention specialist. She encourages her participants and coachees to develop their talents, ask probing questions, and connect to themselves and others. She uses experiences and makes people feel confident and encourages them to experiment and find hidden treasures.
Connect before you lead’ is her leadership motto. She loves theater and dance to get inspired and look at things from different perspectives. Amond her favourite movies are; The Restaurant, Sex Education and Living.
You want Femke on your team when teams got stuck and experience a lack of connection and cooperation. She will gently guide them back on the path of flow and joy, by focussing on good intentions and talents. Femke is brutally honest and doesn’t shy away from the difficult conversations.
Robby Mol
Robby Mol (1964) is a keynote speaker and author of books and articles about “The Future of Work and Pay” (www.flexorfail.org). His 10 years of corporate experience at Caterpillar Inc followed by 20 years of start-up and scale-up show when you meet him.
He has worked as a guest lecturer at IMD Business School in Lausanne, where he also received his executive education after first graduating from Nyenrode, the Netherlands School of Business. Robby has worked and lived across the globe. His moderator, speaker, and coachwork have brought him Boardroom contact with clients such as the Ministry of Economic Affairs in Thailand, IBM, Nike, SNCF, PwC, ABN AMRO, and FedEx.
During the last fifteen years, Robby has participated in many triathlons. He has completed several Iron Man's but mostly enjoys the cross-discipline that takes place in nature. His own enthusiasm sparks lightly and is followed by a deep focus on action and implementation. His favorite movie directors include Lars von Trier, Joel and Ethan Coen, and Wes Anderson.
You want Robby on your team when sharp analysis, life experience, and observation are required. He can listen actively, asks fearless questions, and is motivated to deliver results.
Ronald Becker
Ronald Becker (1970) has been trained as a conductor-singer (Utrechts Conservatorium) and coach-counselor (Europees Instituut).
Ronald is the co-founder, singer, and musical leader in the professional a cappella group Intermezzo. He won many awards and worked with Bram Vermeulen and Herman van Veen. Recently he was director of the Coach College de Baak. He has been a facilitator, trainer and coach since 2004. Currently, he is active in various open leadership courses at organizations such as WMD, Spaarne Gasthuis, Leiden University, and TU Twente.
By applying his artistry in organizations, Ronald always manages to touch a creative source that moves people. He has developed the metaphor of the conductor as a leader into a widely used interactive training program.
Ronald loves leaders who focus on self-awareness and responsibility for society. Music is his lifeline, but the creative energy of nature, personal development, ceremonies, dancing, lightness, and a lot of humor also define him. The film "As It Is in Heaven" tells his life story.
You want Ronald on your team when teams are caught up in too much speed and a sheer practical approach. Ronald will help awaken and develop everyone's creative abilities, in order for new things to emerge; innovation, authenticity, and inner strength.
Marion Jonkers
Marion Jonkers (1988) is an accomplished Interim (HR) Manager with a specialization in leadership and a robust background in learning and development. She has extensive experience guiding change and transformation processes as both advisor and program manager, at Rabobank, Gemeente Rotterdam, Fugro, TWD and many other organizations. Through her training as a systemic advisor/coach and organizational constellator, combined with her corporate business experience, Marion brings a holistic perspective and understands the necessary interventions to initiate genuine change in large organizations.
You want Marion on your team when you need an impactfull strategy on leadership and change. Marion infuses lightness and positive energy into her sessions, making her an invaluable asset in driving organizational success. She has a playful light-hearted style and knows how to navigate complex contexts to arrive at practical effective steps.
Movies and series that inspired her are Borgen and Scent of a Woman.
Marius Gosschalk
Marius Gosschalk (1959) is an actor, trainer, coach, and expert in organizational storytelling.
With a background in Dramatherapy and Change Management, Marius has over a decade of experience helping leaders and teams tap into the transformative power of storytelling. Currently, he teaches at the Storytelling Academy and contributes to leadership programs at the RABO, TWD and Quooker for Unleash, to craft original stories that connect and motivate.
Marius believes that many top leaders underestimate the power of storytelling, and rely too much on communicating targets KPI’s via PowerPoints and Excel. Marius helps them turning vision and strategies into compelling stories that inspire, create direction, and generate energy.
You want Marius on your team when you need to turn numbers into narratives, align people behind a shared vision, and spark the clarity and energy required to drive meaningful change.
Pieter Klaassen
Pieter Klaassen (1984) has been passionate about Martial Arts since childhood, starting with Judo at age six and later excelling in Tai Chi and Kung Fu (Wushu), both in practice and competition. For the past 15 years, he has focused on Aikido, exploring its philosophy and principles.
With a diverse background spanning IT, education, marketing, and leadership training, Pieter brings 18 years of experience as a trainer and coach. He has worked with organizations like Nyenrode University, Unilever, Heineken, Quooker, Rabobank and ASML, translating the philosophy of Martial Arts into practical lessons for leadership and business.
Pieter believes simplicity unlocks movement, creativity, and growth. He helps individuals and teams find flow by focusing on possibilities rather than obstacles. His approach combines thoughtful conversation, creative problem-solving, and embodied learning, using the body as a powerful feedback tool for change.
You want Pieter on your team when you're stuck in overcomplication and need a fresh, simple perspective to create meaningful results.
Mariska van IJzerloo
Mariska van Ijzerloo (1972) studied Organizational Psychology at the University of Texas and the VU, and is a trained System Thinker (IPDP) and Theory U practitioner (MIT). She brings 25 years of experience and specializes in identifying HR and talent change points to drive scale-up growth. She worked for Ampelmann as HR director and alongside Boyan Slat at Ocean Cleanup as Director People & Organization.
Mariska is a positive and joyfull breath of fresh air, who can gather the troops to find practical and lasting structures and programs for tough organizational challenges. She practices touigh love on a daily basis, not shying the difficult conversations and making warm connections at the same time. Sho focuses on the potential of people as the foundation for growth and is passionate about meaningful work in impactful companies.
You want Mariska on your team when you need a structural plan for your leadership development and want this to come alive in your organization.
Marieke van der Giessen
Marieke van der Giessen (1969) thrives at the crossroads of strategy, change, and transformation, bringing over two decades of experience designing and facilitating leadership and change programs. Since starting her journey at De Baak in 2000, she has worked with organizations like Ampelmann, Nationale Nederlanden, SRA, Philadelphia, Signify, and The Ocean Cleanup, helping them navigate complexity and unlock potential.
With a foundation in business economics and a keen interest in Gestalt therapy, Marieke creates environments where people are invited to discover their own solutions and embrace new perspectives. She challenges leaders and teams to learn from diverse voices—clients, employees, artists, professionals, and even those from entirely different generations or industries—broadening horizons and sparking fresh insights.
Inspired by theatre, music, biographies, and art, Marieke approaches every challenge with creativity and curiosity. Her favorite films, Searching for Sugarman and Bohemian Rhapsody, reflect her love for stories that inspire transformation and innovation.
You want Marieke on your team when you need to cut through the noise, get to the heart of what truly matters, and create lasting impact.
