Doing core work can really strengthen the upper leg and hip region as well. One of the simplest I've experienced is Ab Ripper X from the P90X series. 16 min long. Your hips will love you. Yoga is another one. I find videos are convenient for me. A lot of people like going to the gym. I've worked in office environments and I've been self employed. Doing something as simple as push-ups every 45 to 60 min through out the day will do wonders. Or doing plank work for a minute or 2 every hour. Over a period of 4 months of just doing push ups and planks my shoulders, back, pecs and abs never looked so good. And that was just taking a couple of minutes every hour.
People don't realize how easily exercise can be integrated into a day. I also like the Insanity series. I know you only have one healthy leg, and there are a couple of vids in the series that don't require plyometrics and work predominately on core and flexibility.
Best of luck.