If you quit dieting or whatever because of this, then you will only add to your stress... especially with the guilty feelings and the thoughts of failing yet again.
This is life. It doesn't get any easier. $h*t Happens to everyone. To be successful for the longterm, you must learn to maintain your lifestyle changes/choices through every bump in the road no matter how big or small.
I understand... My husband is looking at the potential of getting laid off, he is our only income and am graduating from nursing school in May (which means I don't have much time to work right now); I have a massive amount of money to pay for fees and such for nursing school (over $700, all due this month); and everything that can go wrong seems to go wrong... Just found out that my husband needs $4000 worth of necessary dental work (not cosmetic)...
Need I go on?
My point is that I get it; I know about financial stress and otherwise; I have experience on which to base my response.
I don't mean to sound harsh, but it is what it is and if ANY of us want to be successful for the longterm then we cannot use times like this as an excuse... otherwise there will just NEVER be a "good" time to be on a diet or try a lifestyle change.
Keep your head up, keep your goals realistic, and do your damnedest not to fall back on old habits.
You can make it!