I often try to not even pick up my club when waiting for a slow group in front of me until I'm ready to hit the shot. This helps me stay relaxed and not overthink the shot.

This is also what I was going to suggest. Go ahead and get your yardage, but don't pull a club and stand there with it in your hand while you wait. And definitely don't address the ball until you are clear. I've known guys after long wait to grab a club and address the ball while the group in front is still walking off the green and then stand there until they can hit. Wait until you are completely clear to start your pre-shot routine.

Picture yourself behind a foursome, Cart Path only due to last night's rain. The first player in the group walks over to their ball, lasers pin, then walks back to get club, after three practice swings, the player fails to make decent contact and tops the ball 30yards--new distance and club needed. Hope I triggered some of you!

I definitely feel like slow play after a good few holes changes your rhythm.

Next time, start a conversation with your imaginary caddie about the imaginary crowd awaiting your next shot. Or practice your stinger wedge. Or hit into the group. All better options than getting frustrated.

I’ve had the same problem. Recently I was playing and there was a downhill green that was drivable but there was a group in front of mine so I had to wait 5+ min till I could attempt it and it got in my head so much that I went completely under the ball and went in the trees. Pace of play is so important when you get up to higher levels of playing

Golf courses out here in socal are letting too many walk ons show up to the point that I had a round where I waited thirty minutes to tee off at each hole. It was terrible. All we could do was listen to music and try to kill time while swinging our clubs to stay loose.

Rare I can get a tee time as a single unless playin 9 after 3-5 pm on weekends. Well, some days during the week, but I don’t want to encourage y’all to retire and compete with me for times.
The pros , especially the top quarter of the leaderboard on weekends will typically take 5+ hours. If they can overcome the 6 inch handicap (between the ears) then I should be able to stay focused and not watch the clock. If I have a time limit of 4 hours, I can just walk off having enjoyed being on course, even if it was 2:30 for 9 holes.
That rates are escalating while the number of rounds are skyrocketing annoys me to no end. But I put that in my back pocket, physically and mentally, once out of the pro shop. It is what it is.

Played today and was reminded that golf etiquette is dead. The GM of the golf course we were playing was in the group in front of us. Never let us play thru. They literally held us up for 18 holes. They were hitting it all over the place. Losing golf balls. Not playing ready golf. The group in front of them gapped them by almost 2 holes just on the front 9. Ridiculous....

Whenever I run into these situations, I just know I need to stay focused. It can be easy to start messing around with friends and talking, but if you are really worrying about your score, you have to prioritize that. Take practice swings, envision future shots on your hole, and develop a gameplay for future holes. These tend to help me and hope they can help you too!

As others jave stated it can be very difficult to get back "in the zone" once that zone bubble has been busted. Frustration is never good as it just tenses the body. I just try not to watch the hordes in front of me and play my shot when it is safe for me to do so.

I do admit to being frustrated after following a group for 18 holes when they exit the green on the 18th go their carts and start emptying their pockets, chatting, adding up their score, etc...DO THAT IN THE PARKING LOT!!!