Swimming

I love swimming, as well as running.

After a few minutes of swimming or running, your muscles are going to hurt and you will be so tempted to stop and rest but you keep on going. And the pain seems to recede. And you're happy. Because you think you've overcome the pain.
But then after a while, your energy will suddenly crash and it begs you to stop. And you have no choice but to stop swimming. Because if you keep on going, you're just going to damage your body.

That's how it is with life isn't it.
You're going to feel hurt but you keep on going fighting your way through and the pain just seems to evaporate and you feel happy. You think you've overcome the pain.
But then suddenly, you crash down. And you can't handle it anymore. And you cry. And cry. And cry.

But it's okay. You'll still survive. You just need to rest.