What are the negative aspects of exercise?

Increased risk of heart attack if you overexert yourself while trying to expedite the getting-into-good-shape process.

increased libido…aka “mad rabbit disease”...which leads, potentially, to anything from mild feelings of discontentment to deadly STDs.

There aren’t any, if you follow common sense, do no overdo it, and do not let it become an obsession/addiction.

Injury. Dehydration if you don’t drink enough water of course. But as long as you take precautions and don’t overdo it as @Marina said…I don’t think so.

Sweaty draws

Excessive B.O., an occasional blister or pulled hamstring, an addiction to spandex, and increased energy so you can’t sit around like a slug any longer but must be up and doing.

Of course, not everyone thinks that last thing a bad thing.

Yeah – you can’t stop looking at yourself in the mirror :}

If you do it long enough you will have a difficult time keeping the ladies off of you.

Hunters like to stalk and kill the fittest creatures for the cooking pot, so if cannibalism ever takes root in the world, you also have that to worry about. I’m betting vegetarians that spend a lot of time at the gym taste best!

Increased awesomeness, sudden influx of people attracted you, and reduction in the amount of time spent thinking “I don’t exercise enough.”