You can do all those things without being a cop. I shot more on my own than I did on the department's dime, and that was in a culture that still valued shooting ability. In jiu jitsu, they won't make you wrestle a naked meth whore whose main fighting technique it to bite you like a rabid monkey.
You're almost at midlife crisis time, so be really careful about starting over. See if you can do a ride along, on day shift, not just evenings or nights. Use your company's EAP to talk to someone about job frustration and boredom. Consider seriously whether you want to work nights for a few years straight, or if starting in detention is something you can handle. Remember that promotions are competitive, and assignments are not yours for the asking. You'll be on the bottom rung for vacation selections, possibly for years. Not everyone your age is OK with going back to square one.