get in shape

I dont care how much I weigh, I am not obese or fat, I want to get back the endurance, strength and Physique I had a few years ago. I was really athletic, then I started to work 9 to 5 an after getting home I was too tired to exercise, I also had a back injury which is making it hard to get in shape and prevents me from using my free weights. Nevertheless I have already got back to running about 5k, and soon will be running a 10 k race.