I know that with me this is an ongoing struggle since I started working out again in July after years of being relatively inactive. It is getting easier now, I even took a week off on prupose and gleefully started up again on the start day I had given myself, and found myself restless to start too.
I am trying to shed the last bit of weight so I can be in maintain mode, so my motivation is all around me:
The goal pants. Yes, we all have a pair or five of trousers that no longer fit yet we refuse to throw away because we swear we will fit again.
I have a clothing embargo until I am back on to my normal weight, so wanting to buy new clothes
Pictures of myself when I was in shape on myfridge and bathroom mirror. This helps me stay focused.
Most of all, I just keep at it. I know it is rough, but no one said that it would be easy. I figure the more I work, the more of a habit it will become again and it will be like second nature.
I hope this helps, and good luck!