If he has pretty severe clinical depression/anxiety and it's discovered, he may not be considered for military operations - let alone special operations.

If, on the other hand, he's feeling anxiety because he wants to walk a path different than his peers that could be fostered and encouraged. A mission would definitely give him an edge in mental fortitude. Mission -> college path isn't for everyone. Mission -> military is very possible. If he serves foreign speaking he could also gain a second language proficiency.

If he doesn't want to serve a mission, that's tough as a parent. Him returning home from a mission early may also be worse for him emotionally than never going at all. The new mission age has really exposed the immaturity that high schoolers have compared to even one year removed from high school.

If he wants to do PJ's, he better talk to the swim coach for some workouts in addition to running. If it's CCT or JTAC, just tell him to run every day.

Sounds like a good kid. Good luck.