If you are ever feeling overwhelmed, stop and mentally break your problem into manageable chunks. Think through the steps to take in order to get through the problem, put the steps in order and concentrate only on one step at a time.

Let's say you feel totally out of control and want to get back on track. Everything seems to be working

Start with today and identify what you can do before lunch to manage the problem. Maybe it is walking the stairs one or two extra times. Maybe it is not going to the vending machine on your break. Maybe it is having a salad with Newman's diet Italian dressing at lunch instead of that Big Mac. Don't yet worry about the afternoon and the evening. Start concentrating on little successes to deal with those big problems, and you will find that the big problem gets smaller and smaller, chunk by chunk.