Staying active is one of the best ways to lose weight. Incorporating physical activities into your daily routine is easiest way to do this.
A great exercise that can be incorporated into daily activities is taking the stairs. When you are going up a building, skip the elevator and just take the stairs.
Walking up stairs is challenging for your muscles, but relatively gentle on your knees (as opposed to walking down stairs which is easy on your muscles but damaging to your knees).