Exercise and Fitness

If you can find a cardio exercise that doesn't aggravate the tendon (cycling, or maybe an elliptical trainer?), that will give you something to warm up with and do on off days, that would be good. Other than that, get back into upper body workouts and anything else that doesn't use your achilles tendon. I don't tend to like all the weight machines you find in most gyms, preferring free weights, but the isolation some of them provide can help work around injuries. For example, the leg extension machine doesn't rely on your feet/ankles, so would be a good subsitute for a squat.

Current research is showing that strength training is more effective at burning fat than aerobic activity. Your metabolism stays high for hours after a workout. And adding muscle is adding extra fat-burning capacity to your body.

I have a bad habit of going regularly to the gym for 4-6 weeks, then something sets me back (maybe a cold, extended travel, or whatever) and before I know it it's been 2 weeks since I've been to the gym, I'm eating shit, and putting on weight again.

My main advice is just to get back at it with something. Take it easy, keep it fun. Before you know it you'll be back in a routine.