How do you stay optimistic

I’m nearly 21, never had a job before due to a previously unmanaged + undiagnosed medical condition condition. Now I’m finally fit to work, but no one is hiring. What’s the point if all HMs are just gonna see me as a lazy bum who chose to not work? What even happens to people like me?

I just got rejected by Mcdonalds twice, I don’t know what else to apply for.