I’m not depressed (at the moment, well maybe a little), just feeling philosophical.
Edit: the idea of this came to me because I was pondering why people fight so hard to beat diseases and live a few more years. What are they planning to do? Why exert effort just to be here longer when you don’t have a reason?
Just why?
Everything is meaningless, nothing matters. Therefore whatever you decide is important is all that matters.
You can look up optimistic nihilism if you want
Absurdism is another (IMO better, but that’s just me).