Anybody can have a bad day where they go off course. I think the important thing is to recognize that going off course is part of the process. The trick is to pick yourself up, dust yourself off, and get back to healthy habits just as quickly as possible. I think a lot of people trying to lose weight fall into the trap of thinking, "I blew it today, so what the heck, I'll just go back to eating as much crap as I want because now I've blown it." That is defeatist thinking. One bad day does not ruin the move towards a healthier lifestyle. It's just one bad day, and we all have them. Change is hard, and few of us are able to march into a healthier lifestyle with no bad days along the way. Another point is that we should make our healthy habits as enjoyable as possible, so that we want to stick with them.

I can't remember who said it, but some actor/singer who is in great shape said "I eat mostly good, most of the time". Nobody is perfect.

In a sense there is a finish line because once you reach your goal, you won't be so hard on yourself for the occasionaly slip up so long as you are good "most" of the time.

For me the motivation is purely in seeing the weight come off. Eating healthy and watching my portions are really working for me. Every morning I step on the scale and am surprised/excited by my weight loss. The decreasing numbers really motivate me and keep me going. Of course, I will eat the occasional treat as I don't deprive myself, but sometimes I think twice before I eat it and think ahead to what the scale might say the next morning.
Maybe that might help you as well. If you are doing great for four weeks, treat yourself to a treat and then continue for another four weeks.

Is anyone perfect?
I know I'm not!
I look at it this way.
I'm happy If I keep to my healthy eating goal 90% of the time.
That means 90% results not 100%
If I keep my goal 75% of the time, that means 75% result.
As long as you keep striving for close to 100%.
Don't quit, keep going!

thank you for the comments. I am now back at the gym.. however I'm starting small. Went for a 10 min run/walk. I am planning to do 10 minutes of cardio tomorow and 15 minutes of strength training

I take a journal with me and keep track of what I do at the gym. It is also where I weight in each day.

That works for me. Seeing too many days go by without an entry in my journal motivates me!

Along with the bad day thing, you can have a "bad meal" and then go right back to eating like you were suppose to the rest of the day. I know for me personally I have craved something that wasn't part of my plan for eating that day and I went ahead and ate it because if I didn't then I would have eaten everything else and still ate the same amount of calories, but instead of letting that ruin my whole day I picked right back up and ate my plan the rest of the day.

I have long held to the principal of "good enough". If we try to be perfect we will just drive ourselves crazy.

Not that I mind an occasional journey into crazy land, I just want such a trip to be on my terms!