The main component to getting 'in shape' is generally cardiovascular activity. The feeling of being 'in shape' comes from not being fatigued while doing your activity of choice.

The best way to improve your cardiovascular health is to run. Run in the street, run on a treadmill, whatever. Get your heartrate up, and keep it there.

As for flexibility, you may want to talk to a friend who does yoga or pilates, and get into a class. Or you could simply do some static stretching at home when you have time.