Having recently gotten back into regular martial arts training, I wouldn't say I have a real routine down yet. But I do have a few good exercises at home that do a world of good keeping me in the fight without injury. I have something called a "Power Tower" in my room, which is basically a frame with a pull-up bar and 2 lower pegs for dips. I've attached "ab-straps" to the pull-up bar and do an exercise where I suspend from the bar and pull my knees up to my chest, working my abs. Right now I am just doing 3 sets of 10, maybe 2 times per day, to keep my lower back in good shape. I've recently started adding some ankle weights to the mix, or simply doing more reps. It is this exercise that I credit the most in my recovery from the lower back injury that ended my Shotokan training. Apart from that, I have an exercise my current chiropractor (who also happens to be a TKD 4th Dan) recommended to me to help with my posture and upper back problems. It basically involves leaning into the corner of a room with my arms high and spread far apart, and then pushing myself back up (sort of like a wide push-up into the corner). Generally I will do this 20 times, several times per day. Aside from that, I don't have much else going on right now. I have yet to get back to a running routine. I also would like to get back into the habit of swinging some weapons around in the back yard. I still remember a few bokken and jo drills from my brief time in Aikido, and even though it may not directly translate to TKD techniques, it is still a good little drill to work on mental focus and increase the flexibility and endurance in my arms and shoulders. And it was nice because it was something I could easily do in the dead of winter, even when wearing layers upon layers of clothing. Plus I have a rather tall stump in the backyard I will practice light, controlled kicks on. Sort like an all natural makiwara.