Use the time you save for commuting for some exercise!
Here are a few ideas - please speak to your doctor before you adopt any kind of strenuous exercise regime.
Please wear trainers or shoes with a non-slippery surface for this exercise!
Rest with your upper body on a wall and slide down slowly until your thighs are in a right angle with your lower legs. Hold for 20 sec. Rest and repeat 5 times.
Planks are one of the most reliable and trustworthy core exercises, primarily because they hit nearly all of the muscles of your abs! Make sure you keep your butt down, and your back as flat as possible.
3 one-minute planks (try to hold for 1 minute, if your form starts to falter, rest for 5-10 seconds then resume your plank for the rest of the minute)
Try to bring your knees as far up to your chest as you can (without kicking yourself!), and remember that the faster you go, the more you will sweat! Start with 10-15 per side and when you get better do as many as you can within 60 seconds!
Burpees will wear you out, I promise! Step one to five should be one series of fluid movements. Start with 10.