I do BJJ and once you get into it, it is extremely fun and rewarding. Strenuous physically. Mentally, extremely deep, popular with tech folks because although you have to be in shape skill development dominates. Strength will always be an asset. So will cardio, but skill dominates. Plus close human contact releases oxytocin and other hormones. And the physical activity does the equivalent of a runners high. And the mental activity gives you intrinsic learning rewards. I suppose you can burn out on it, it can be very frustrating at times, but once you get past the first humps it is golden.
I loved judo for this reason, although BJJ might be less dangerous. Exhausting; You take hits (unvoluntarily… maybe); You learn gestures. And more importantly: You learn with your body. I think our bodies demand to be used ;)
Socrates was right! There’s no mind without a strong body! (for a man at least).
Test is definitely a factor in working out and feeling good for all men, but especially young men. Plenty of women enjoy BJJ for many of the same reasons men do though. BJJ is relatively safe. You will end up with injuries, but it is worth it for me as a desk jockey. :)