It is no surprise to most BJJ practitioners that there are massive benefits both physically and mentally in training. BJJ can teach people to be more confident, to be more courageous, to control one's emotion, and to preserver through dark times.
When your feet touches the mat, every non-BJJ worries quickly slip away. Why? Because there is a conscious being trying to strangle you or break your limbs. This leaves no extra time to think about how Bob insulted you at work or how you didn't get that promotion you wanted. Your mind is focused on how you can control and dominate your opponent. Training is the one thing that all practitioners can control. You can be as intentional and methodical as you want. Your progress in BJJ is largely determined by your input. It is for this reason that BJJ can help in over coming many adversities. Because it gives a sense of control when all other things are out of your control. Below is one example from James Clingerman, who recovered, after getting shot point blank, with the help of BJJ.