I find these sorts of platitudes totally useless to someone with a practical and well-defined problem: can't find a job because he can't pass a background check. As a hypothetical (I have no idea if this is possible), maybe there's a way for an official diagnosis of his neurological condition to enable him to circumvent/solve the background check issue.

His question was about living a fruitful decade despite the difficulties. Getting a job doesn't necessarily make your life better. Helping other people does. For the skeptic, there is only one way to find out, however.

I don't understand this claim. I've been depressed at a time when I was very much "useful" both professionally and in a relationship.

Being in demand (or needed) is sort of like having money: it doesn't have any direct correlation with mental health.

How about volunteering? It is one way to make others happy, and is deeply rewarding. Meeting new people and being a part of the community is essential to sustain happiness. If you have a dark past, it can be difficult to open up to new people. So it might be good if he tries to volunteer in communities which deals with such problems. Helping out organize events, speaking about he overcame his difficult times could be good opportunities to explore. The social connections can lead to positive professional growth as well.