"Everything kills you eventually; it's better to be killed by something you love." — Charles Bukowski
Remember the feeling when you're sitting in a class you have no interest in — ten minutes in, you're yawning, exhausted, and sleepy, without any exertion at all.
On the other hand, you're working on a project you deeply care about. You work ten hours flat, you haven't eaten, you haven't socialised — but still, you're energised. You don't want to sleep; the vision keeps you awake. You just want to keep at it. You feel like you can go on forever, physically and mentally, and hours seem like seconds.
Similar things show up in most things we do. When you talk to someone you love, you can talk for hours and it feels like minutes have gone by. But talking to someone at work, ten minutes start to feel like forever, and you're conscious of every passing minute.
How much exertion you feel is quite a function of how deep the meaning or purpose you find in what you're doing — not the time and effort you put in. It sounds counterintuitive, not quite in line with the basic laws of energy dynamics, but that just shows us the non-linear way our minds work, and how little we understand it.
I will venture to say this: it is one of the most beautiful things to experience — being exhausted, if possible, while doing something you love and are deeply passionate about.
About something you have infinite energy for, even after working a lot, even against seemingly insurmountable obstacles, and your very human limitations. Despite all this, meaning brings joy.
That's a beauty just by concept.
"A man who has a why can bear almost any how." — Friedrich Nietzsche
When you work on projects you find deep meaning and purpose in, you can bear almost any circumstance or obstacle — and you'll go further than you ever would on a project taken on out of obligation. Sometimes to the extent of personal oblivion, like the scientists who gave their lives in exploration, innovation, and invention.