Marshall offers spiritual mentorship that draws on over 20 years of experience with and trainings in a wide variety of psychological, therapeutic, spiritual, philosophical, and inner work modalities.
- The Diamond Approach (Over 15 years)
- The Enneagram (Over 15 years)
- Many kinds of meditation
- Vipassana (Buddhist)
- Microcosmic Orbit (Taoist)
- Kath / Hara (Diamond Approach)
- Zazen / Being Meditation (Zen)
- Internal Family Systems
- Bioenergetics (Alexander Lowen)
- Gestalt
- Somatic Experiencing
- Continuum Movement
- Inner Relationship Focusing (Eugene Gendlin)
- Self Acceptance Training (Dick Olney, Cherie McCoy)
- Various Breathwork modalities (Reichian, Holotropic, Wim Hof, Biodynamic)
- Object Relations Theory
- Family Constellations
- Integral Theory (Ken Wilber)
- Spiral Dynamics
- Soul Without Shame (Byron Brown)
Marshall has also studied the Enneagram for 15 years. Marshall worked for the Enneagram Institute for nearly 4 years, where he created the technology that powered the RHETI (Riso-Hudson Enneagram Type Indicator). During that time, he attended several Enneagram Institute trainings as part of the Riso-Hudson Certification program. Marshall is also a member of the International Enneagram Association and has participated for several years in reviewing speaker proposals for the global Enneagram conference.