When the sun goes down, another great reason to live in Denver is the swing dance scene, if you're into that. You can lindy hop four nights a week in Denver; more if you're willing to drive to Boulder or Colorado Springs.
Of course, it takes energy to enjoy long walks and lindy hopping on a school night. My best suggestions for increasing your energy if it's flagging: stop eating sugar and flour. Start eating a high-fat, adequate protein, high-nutrient diet. Eat when you're hungry, rest when you're tired. If there's still no wind in your sails after two weeks, look into which vitamins and minerals you might be low on. And if that doesn't work, see a doctor--you may have a hormonal problem or an illness.
That's it--my big suggestions. But that was enough to allow me to give up four-hour naps on Sundays and early bedtimes on dance nights.