Working Out

I have been doing this interesting thing called "sprinting" for the past couple days.
For those of you who don't know, sprinting consists of running forward as fast as you can for an amount of time, pumping your arms and legs to use maximum energy so that you can propel yourself forwards at around 20 mph.
I do this not for the feeling of wind in my hair, although that is nice, but to get myself in better shape.  Sprinting is a good workout for those of us who play sports, like soccer, or hockey, or football, or track and field (especially if you run the 100).  However, it causes pain for the rest of the day, sometimes even the rest of the week.  My question is relatively simple on this subject: Where is the line drawn between taking care of our bodies and self harm?

Now, I believe that we should take care of our bodies because they are a creation of God and we shouldn't neglect that.  If we truly love God then we will want to take care of the things He has made for us.  That should be a given for Christians.  Just like we should take care of the earth and not litter (while not making sustainability a religion (another topic for another time)) we should take care of our bodies and not let them go to waste.  But in taking care of our bodies, that also involves keeping our bodies from harm.  And when we workout, and we run, and we try and get stronger and in better shape, it takes a lot of pain to get there. 
Is that what God wants us to do to take care of ourselves?  I don't know what God thinks.  But what I guess I think is that we shouldn't rejoice in pain, but pain is necessary to get to where God wants us.  Sometimes that is physical pain, sometimes emotional.  I do not believe that self-flagellation is where God is calling us.  That is the opposite of taking care of our bodies.  But man, God needs us to be able to take control of our lives while at the same time being able to relinquish control to Him!
If we want to take care of our bodies, a little pain is necessary.  We shouldn't be trying for pain, and there is a big line between what is ok and what isn't (for example, some runners run until they throw up and then they call that a good workout.  That is not good.  Especially for those of us who hate throwing up...).  But sometimes pain happens.

The key to being successful in keeping your Christian life together with that is to be giving the glory to God, keeping your Christian life above whatever sport you are playing, and watching your temper while playing.  Dang that is hard.  Such is life.  And if your life following Christ is easy, are your sure that it is Christ you are really following.

(I like Calvin and Hobbes)