There's a famous story of Adam HaRishon, the very first human, who wondered this same thing. It actually came out of a little know creation story.
The first animal that God created was the dog and said to the dog: 'Sit all day by the door of your house and bark at anyone who comes in or walks past. For this, I will give you a life span of twenty years.' The dog said: 'That's a long time to be barking. How about only ten years and I'll give you back the other ten?'
So God agreed.
Then God created the monkey and said: 'Entertain people, do tricks, and make them laugh. For this, I'll give you a twenty-year life span.' The monkey said: 'Monkey tricks for twenty years? That's a pretty long time to perform. How about I give you back ten like the Dog…