Marten is a registered psychologist with the South Australian Psychology Board, and is a Member of the Australian Psychological Society.

He has trained extensively in counselling, including family therapy, individual therapy, and relationship counselling and health. He has also been involved with training and supervision of Counsellors and Family Therapists at the University of South Australia, and at Bower Place. He is an executive Board Member of the Australian & New Zealand Journal of Family Therapy.

Marten has worked in private practice and in the non-government welfare agency field. His therapeutic work has focused areas relating to the parent-adolescent relationship, depression, anxiety, sexuality and sexual issues, grief and loss, abuse, drug & alcohol problems, and general life choice issues.