If you find that you can only focus on guitar for 2 hours, then allow yourself to stick to that. 2 hours of focused practice (even 1 hour) is much better than 3 or 4 unfocused.

I go through this myself actually. Part of you may be fearful that it's going to be hard, a lot of work, you won't accomplish much, etc....all sorts of negative stuff.

Do you have a plan? Goals? Without these you will progress slowly and won't feel much satisfaction, and that makes it feel like work!

Make a plan and set some long, near, and short term goals. Make them realistic! As you accomplish these things, you'll see progress and it will encourage you to continue. You'll have things to celebrate!!

Allow flexibility in your plan and goals. Don't beat yourself up if you skip a day practicing or you don't meet a goal according to your schedule.