What is the effect of increased exercise on the burned out? I've started getting 20-30 minutes of additional almost daily exercise by bicycling for transportati

What is the effect of increased exercise on the burned out? I've started getting 20-30 minutes of additional almost daily exercise by bicycling for transportation, 10-15 minutes and 2.5 miles each way. I wouldn't say that I am a lot happier or that I'm sleeping earlier, but my legs are tired all the time and I derive some intellectual satisfaction from the perceived increase in my health. The psychological reality has not quite lived up to the hype.