I know it's probably not what you want to hear, but exercise makes you happy. Just think about it. You roll out of bed early, after a good night's rest, pull on your spandex (or sweats, or yoga togs, or whatever), and jump on the treadmill or head out the front door for some speed walking.
You huff and puff, and think "I'm so tired, I'll just do a short work out today." But then you get going, and your blood starts pumping. Your muscles get warm and your forehead starts to "glow". You reach your twenty minute mark, and think "I'm feeling pretty good. I can go a little bit longer." You get home and stretch, feeling that warm after exercise glow, and you smile.
It feels good to accomplish something. It feels good to get your body moving. It feels good to breathe deeply. It feels good to be doing something that you know is right for your body, and for your mind.
"One of the most overlooked things that people can do to make themselves happier is to exercise regularly. Vigorous regular exercise is a pretty good anti-depressant, and it just helps you feel better about yourself and your life overall.
When you exercise regularly, you tone your body and metabolism, regulates stress hormones like cortisol, and promotes the release of endorphins (morphine-like substances that your body naturally releases when you exercise)." mentalhelp.net
Exercising regularly is not only important for you, but for your children. They need to see that health is a priority and that exercise is for everyone. With the rising levels of obesity in our country, these lessons are even more important. If a person, child or adult, is getting the exercise they need, their bodies will be better able to handle the occasional junk food meal (or holiday). Your children will be happier, you will be happier, you will sleep better at night, and you'll get to buy new shoes a lot (because you'll be wearing out your exercise shoes, of course).