First and foremost, exercise is the best choice for healthy living after paleo.
If I was you I'd start of slow, stretching is really important and essential part make sure you do it after you finish your exercise session. Second thing, bodyweight exercises are also extremely helpful, even the most advanced bodybuilders still do push ups, pull ups and Arnold Schwarzenegger recommends them in his book.
I'd recommend improving your flexibility first, because resistance training can hurt your joints if you don't do the exercises correctly.
I've found one handbook for improving your physical condition, if you want the link send me a message.
Best of luck!