When we push ourselves really hard, we tend to push our limits and in going beyond them, we injure ourselves. However, if we were to control that and continuously work at a slightly harder intensity, we can improve ourselves, because our body will adapt and become stronger, which means that the pace would go up, since you're constantly improving your running efficiency. As your body adapts, you continuously push yourself and with consistent training, you're able to grow properly and not only become fit, but healthy. You won't be hurting yourself by pushing yourself to improve. Rather, you'll end up growing in both fitness AND health.
Most people don't take care of themselves when they're pushing towards their goal. They see the goal and rush towards it... but sometimes, it's important to be able to take your time and do the deliberate and correct steps that gives you a solid foundation as well as the growth.
Once again, balance comes into place, as we work towards the end we desire. Balance is essential in order to safely achieve our goals.
Today, my little run between classes took only 29:48 out of my day, running 4.29 miles, an average of 6:57 min/mile. It's always nice to run shorter distances like that.