Start by going to your local police department and see if they offer a police explorer program. Go for a few ride-alongs if possible. You will have a much more informed understanding of what the agency does.
Did you ask the examiner what part caused you to fail? Failing a polygraph does not necessarily ban or forbid a person for life from re-applying or applying at a police department.
After the case is closed, it gets split up. Most of it will go to the feds, the rest of it goes to the department that seized it. The money will be use to purchase vehicles and equipment.
I'm into crossfit. I think it's a great workout that covers all aspects and it keeps me in shape. I keep the carbs down, eat alot of fresh fish and fruit.