If it's as bad as you suggest it is, try breaking things down to their most basic steps. For example if tomorrow you really want to start working out, don't look at it as, 'I will workout tomorrow', look at it like this:

Step 1: I will get out of bed a 8.00am.

Commit to that choice only. Set an alarm. Do it. Once you're up on time then your next step is: Get dressed in workout gear. At this point you're probably going to REALLY start reconsidering working out.

"I just want to go back to bed for 5 minutes." "I just want breakfast first." "I just want to play with that cat."

NO! Don't think about working out at this point. Your next thought is to take your next very small step: I'm going to walk outside to my car. Do that.

Next step: I'm going to drive to the gym.

Next step: I'm going to walk inside the gym.

Next step: I'm going to get on the treadmill and commit to 15 minutes ONLY.

Etc, etc, you get the picture, and this strategy of basic, baby, small commitments all day should be applied to everything you do. Commit no further at any point than simply STARTING the next small step. DO NOT get out of bed tomorrow and envisage the bigger picture - the treadmill. That will scare you off. Envisage putting your workout clothes on ONLY because that step is small and it is easy, so your lazy mind will allow for it.

I think you'll find by breaking big tasks down to their most basic steps, you'll be happier to move forward. It's easier to put a pair of shoes on than it is to hit a treadmill. It is easier to walk outside to the car than it is to hit a treadmill. It is easier to walk inside the gym than it is to hit a treadmill. It is easier to... HOLY SHIT I'M ON THE TREADMILL. How did I get here?

Good luck.