We've all had the feeling before. You know that you have everything to be thankful for: a great significant other, a loving family, a pretty good job, and a healthy working body. Still, you keep having this nagging feeling that what you have just isn't enough. Sure, you can be happier by making some life changes, but the easiest way to be content with your life is to adjust your perspective and daily actions, which will make you more likely to appreciate what you have. So how do you...