At what point do you give up...?

I feel like my entire afternoon is dedicated to trying to get my 2 year old to take a nap. After lunch he lays down and falls asleep. Within 10 minutes he’s up screaming. I go back in there and comfort him back to sleep. He’s up again in less time. Repeat the process for probably an hour or two. He’s exhausted. I’m exhausted. But he still needs a nap because if he doesn’t get one, he’s over tired at night and won’t go to sleep until like 10pm. At what point do you just give up with the nap? I’m so exhausted. I don’t know why he won’t stay asleep.