Antidepressants

Is it wise to go on antidepressants? I know I have a depressive personality. I also know that I am capable of being highly functional and reasonably happy when not on antidepressants. But I've found that's only possible if I'm getting fairly intense daily exercise. If I stop exercising, I often experience a huge crash in my emotions. I don't want to take antidepressants instead of exercising, but it might be nice to have some insurance in case life gets in the way at times. I don't want to suddenly experience a huge crash come exam time just because I'm too busy to work out.

On the other hand, I have a natural reluctance to use antidepressants. Will they change me in some ways that I won't notice? Will I ever be able to stop taking them once I start? I'll have to decide soon.