Just my opinion...but when I reflect on slow play ruining my momentum, I usually find that I let it ruin my momentum. If I'm waiting on a group, I try really hard not to focus all my attention on the fact that I'm waiting. I bust out the ol' smartphone and scan Instagram. I walk around a little, I talk to another person in my group, I watch another group on another hole hit tee shots...but sitting in a cart or standing by my bag and staring at the group ahead of me usually hurts how I'm playing more than the fact that they're slow.