The best therapists produce results 80-90% of the time — but there aren't nearly enough of them. Scalable interventions like books and podcasts only help a little. Mark's co-founded an AI app called Purpose designed to bridge that gap: deeply personalized, emotionally challenging, and available to millions. During beta testing, 20-25% of users cried. His own wife cried using it. He calls it potentially the most important thing he's ever built.