Our body is made up of many parts, and we are made to adapt to our environment. Constant stress to our body will eventually cause our body to be able to handle it because it gets used to what you do. Almost every day, I would do pull ups and push ups and I've been able to little by little, raise the numbers of each. As of today, I'm up to 25 pull ups and 59 push ups in one max set. I cycled for 20 minutes because before I went to the gym, I played a good bit of indoor soccer. It's nice to be able to work on my speed using another sport because the amount of work I put into pushing myself is more enjoyable. Sprinting at top speed for the sake of getting faster isn't as appealing as chasing after a person who has a soccer ball with them. This constant push has become a normal thing for me, so now I don't really 'tire' as much because my body is so used to the activity level.
Now as I increase my activity level, my body needs to adjust, and each time I adjust it, my level of fitness rises to a new level, allowing me to continue on. After my 5k on August 25th, I plan on starting each day with a certain mileage, to get my body acclimated to continuously run. At first, it'll only be 8 miles a day, but eventually, I'm going to go up above ten miles a day and go on towards 15 if I have the time to do so. As I work out at the gym, my mileage may not increase too much, but because of the constant running I would be doing every day, my body would eventually get used to it, understanding that it's just another day, so that I need to get used to that. Now of course, I'll have to balance my social time because of this, but with a goal in mind, I'm planning on moving onward and running longer.
Our body is amazing, but at the same time, it's not unbreakable. When you're adapting or acclimating to what you're doing, if you go too fast, you'll end up hurting yourself and fall back to square one. It's important to be able to push forward at a reasonable pace, so that you would be able to adjust and adapt to where you need to be.