You walk into the woods. You find a massive tree that you want to use for lumber to build a house. All you have at your disposal to take this tree down is an axe.
What is more realistic: to realize this is going to take a very long time, so you're going to settle in for the long haul and use your time and energy as wisely as possible. Or to go out pumped to take this tree down and decide that you won't be satisfied until it comes down, and it better come down by nightfall!
So it is with improvement in golf.
The tree is a really big goal of yours. And the axe is practice. You won't be able to chop a giant tree down in one day, and you won't be able to accomplish your big goal in one day. Yet why do we get disappointed and discouraged when it takes longer than we want?
I'm going to linger on the tree analogy just a little longer. The thing about chopping down a tree with an axe is you have no clue how long it's going to take for it to come down. You have no clue how many chops will get that tree falling. But you do know what you have to do on a daily basis. You have to show up and chop at it, and then show up again tomorrow and chop, and show up again the next day and chop. Because every day you don't chop is another day longer it will take for it to come down.
So back to your big goal. Let's say your goal is to have a scoring average of 71. Now that's a very good scoring average and would do very well in most tournaments you play. But it seems simple, like you should easily be able to average 71 for a season. After all you've shot better than 71 a lot. So you play for an entire season and you look back and your scoring average was 74.5. "Ugh! Last year my scoring average was 74.25! Did I just get worse?" Most people go out the next day huffing and puffing and just try to push the tree down with their own strength. And no doubt get even more discouraged.
So what do you do to combat the disappointment? You speak truth and logic to yourself. You realize how long it takes to improve just a little at golf, which has thousands of variables every single day. You realize what it actually takes to lower a scoring average. It takes every part of your game (or at least most parts) to be better than they are now. This takes a holistic approach to improvement, and it will require a lot of time. You can't improve everything dramatically in one day, or even in one month or one year sometimes. But that one one month or one year is made up of tiny little blows with your axe, aka diligent practicing the right things.
And don't think simply putting in the time will get you to where you need to be. It has to be quality time. Simply putting in a ton of hours of mindless, fruitless work is like hitting a tree repeatedly with the handle of the axe. All effort and no progress. You'll just wear yourself out and get even more discouraged.
Finding that balance of quantity and quality, and a very high amount of quality, is going to be the repeated blows that will take the tree down, aka help you reach your big goal.