If you want to lose weight, come up with a goal and tell everyone. Tell your friends, your family, your coworker, post it on online social networking and microblogging services, etc. The more people you tell, the more motivated you'll be. People naturally hate looking like fools, and if you don't lose the weight like you say you're going to, you'll look like a fool. This will help keep you motivated even when things get tough.
If you are overweight, consider weight loss as a way to ease joint pain. If you begin making changes for a healthier lifestyle, your body will benefit. Losing weight minimizes pressure and strain on joints, and is worth trying before considering more radical chemical treatments. Sometimes, all you need is a change!