I think one of the key things to being successful at this is having a plan. This forces you to focus and keeps you accountable.
For me, this is something I have been lacking since I got off the wagon. I still work out occasionally, but I am just arbitrarily deciding what to do on a day-to-day basis. This has kept me from being outrageously unhealthy, but it hasn't allowed me to get where I need to be.
I have decided to make a few changes that will help me stay healthy, and have fun doing it! I am going to start doing active things with friends. Right now, most of my time spent with friends involves eating and/or drinking, the two things that are deadly to getting healthy. I have started to plan morning/weekend surfing outings, and other more active things to do with friends.
In terms of keeping myself accountable, I have started working towards completing another half marathon. The last one I did was about 6 years ago, and it did wonders for me. I am enjoying getting up a little early during the week to run or walk, and taking some time to stretch and actually have a good breakfast.
I also plan to continue weight lifting twice a week, though I'm not going to track myself too much or focus on it as much as the running.
Food-wise, the last few days I have really started to think every time I eat. I recently read that the main difference between skinny people and fat people is that before eating, skinny people picture how they will feel after eating (bloated and sluggish vs. energized) and fat people picture how eating the food will be (boring vs. delicious). That's a generalization, and obviously healthy food can be delicious too, but by picturing the enjoyment during eating, there's no reason to stop. By picturing the enjoyment afterwards, it's easy to avoid the bad foods. So, my plan going forward is to have a happy balance of enjoying the food, but staying in control. I will never fully have the mentality that food is just for sustenance. I enjoy eating, I enjoy cooking, and that's not going to change.
Let me know if you have any thoughts on this!