Regret at the end of everything.
In what’s a short amount of time on the cosmic scale, Earth’s inevitable death will come, along with everything I left behind. No human will be there to remember me anymore, all my ideas, memories and thoughts disappearing without anyone to wave them goodbye.
Demotivating and sad, isn’t it? To think nothing lasts forever, and at some point in the future, it won’t matter.
I disagree. Everything has an end, but that’s what makes the part preceding it worth enjoying.