One of the best qualities in golf is patience. Patience is the key to staying calm and keeping emotions at bay.
Golf is not a game of hitting as many of the best shots you can consecutively, its really about managing all the bad ones in the best possible manner. If you have a string of bad holes, are you going to become emotional, get mad, swing faster, lose focus and break your routine? Or are you going to stay cool, keep your focus, and keep your tempo consistent? To do the latter is hard and it takes patience.
Watch the pros; they have patience. You don't see them lose their cool too often and you definitely don't see them break their routine. They stay patient and do so with practice and experience.
Take the time to practice patience next time you go hit golf balls, play a practice round, or chip and putt. Practice by ignoring the bad shots and repeating your consistent routine exactly the same way every time. So if you hit a bad shot, don't get pissed and rush through the routine on your next shot. Slow it down, do the routine carefully, then hit the ball.
This is just a very small step that will help with a lot of other aspects of your game. But stay focused on this, don't forget it, you need to turn this into a habit. Once you do, you will become a grinder. You will be able to go out and not play your best and still win. That's what golf is about.