I feel like nothing matters, and it's hindering my motivation

I feel like existing is meaningless. It won't matter how well I do in school, how many friends I make, what skills I learn, ect. I ultimately have no goal for my life and am stranded on this ball of rock, water and other elements floating through the seemingly endless void of space. Just a few weeks ago I used to be atleast somewhat motivated towards self-improvement.

Eating more healthily, doing more schoolwork at home, going out more, eating and drinking less junk. Now I don't feel like doing any of it, just thinking "Nah, too much work." "It won't change anything" "I'll just continue my old ways" "It doesn't/won't matter". Idk if I'm just tired, lazy, depressed, anxious or whatever's my issue, but there are things I wanna do but my mind is blocking me from. I could force myelf to work with these things, but it won't stick when my mind isn't cooperating.