My number one problem. Which is why it's embarrassing for me to tell someone I've been playing guitar for 18 years because they assume i must be a pro, I just consider myself an intermediate player. Remembering the idea that it can just take 5 minutes to keep myself on track. For example, my warm ups are averagely 5 minutes so after i do those im stuck and want to keep on playing! and if that still doesn't help, what i do is that i take baby steps mentally. Meaning, i think about guitar, i touched the guitar, and then i do warm ups hopefully that made sense:) keep rocking! this will take time to adjust but you'll eventually overcome it, i believe in you!