is there such a thing?

I mean, you can overdo it and have a heart attack, but as long as you survive, it should be ok.

I know that I am completely wrong in saying this, but I don't know how wrong.

I ask because I hit the track this morning. I haven't trained seriously for MA in 2 years, and I haven't trained at all since last October. I went to the track to do a little jogging. I basically did 1/4 mile jog, 1/4 walk for a bit, then 1/8 mile jog, 1/8 mile walk, then by the end it was more like 1/8 mile jog, 1/4 mile walk. I did this for around 3 miles. I know I'm most likely seriously out of shape. Anywhos, that was this morning and this afternoon I was thinking of doing some laps in the pool for a while. Would I be overdoing it? And does it matter for someone who is just starting to train again? I figure, I didn't really even do that much on the track that it should be ok, but I did feel that jog in my quads so I'm also figuring that I did do -something-. Thanks.