It's Monday, so you might not feel like smiling.  But did you know that forcing yourself to smile can actually make you feel better?

Psychologists call it the "facial feedback hypothesis."  Basically, the expression on your face is affected by your mood . . . but it also directly affects your mood.

In other words, if you force yourself to frown all day, you're more likely to be miserable.  And if you force yourself to smile, you're more likely to enjoy yourself . . . even at work. According to here are five more reasons to smile.

1.)  It Makes You Seem More Trustworthy. In one study, participants were 10% more likely to trust someone if that person was smiling.

You obviously don't want to overdo it though, because constantly smiling is just weird.

2.)  It Makes People More Likely to Forgive You. You shouldn't look happy about making a mistake.  But research has shown that if you force a smile while you're apologizing, people are more likely to give you a break. An embarrassed smile can be especially affective:  That's where you smile and look down at the same time.

3.)  It Makes You More Insightful. In one study, people who smiled during a test performed better on tasks where they had to concentrate on the BIG picture . . . not just individual questions.

In other words, smiling helps you see the forest . . . not just the trees.

4.)  It Makes You More Approachable. This one's not that surprising, but researchers found that when a man and a woman make eye contact at a bar, the guy only approaches her about 20% of the time.

But if they make eye contact and she smiles, there's a 60% chance he'll walk over.

5.)  It Might Add Years to Your Life. Scientists at Wayne State University in Detroit looked at pictures of baseball players taken in 1952.  And the ones who smiled when they had their picture taken lived an average of seven years longer.