Without a gym - wall sits*, lunges, squats. If you can get some dumbells you can add resistance to your lunges and squats and also do dumbell deads.
For the old mid-section, crunches are good. Dips are also good and do stuff for your upper body as well.
Some sort of aerobic conditioning is required: whatever turns your crank - bike, run, stairs, skipping, swimming.
*Wall sit: back against the wall, thighs horizontal, shins vertical, hooooold it - if you can go 10 minutes, congratulations - you're probably on a national ski team. I can do 3 before I collapse with shaking jello thighs.