I think you'll get a lot of good advice about technique and mental attitude, and there are important things to be said about these things.
But I'm going to suggest you go on a crusade to increase your hand endurance. There is nothing like being able to hang on to improve your footwork, body position, and mental outlook. Not to mention you have the gas to get in higher gear and have enough reserves to climb down if things aren't working out.
There's a ton of advice out there on this subject. I'm interested myself, since it has turned out to be very hard at my advanced age to recover hand endurance after seven months of being out of action from my ACL repair. I can only say that many of the recommendations from books and the internet I've read haven't really worked for me, perhaps because they are really aimed at a much younger and much more capable person. I think all you can do is read up and experiment with a bunch of things and try to discover what works best for you.
Here are three observations that may or may not be of any use: (1) You can go a long way in the Gunks if you can endure and recover on big holds. So don't make the exercises all about fingertip stuff. (2) Spend some time climbing up and down routes in the gym. (3) Outdoor advice: don't be pulling on horizontals when you could be hand-jamming or finger-locking the same features. And if a horizontal tapers to the left say, then you can often get a sideways jam or lock and lean left against it to rest in a spot where otherwise you'd be gripping hard by pulling straight down.