Weight loss is not as simple as eating less and exercising more. You will most probably face some crushing setbacks along the way, and you need to realize they are part of the journey. Life will happen and you will experience some emotionally and psychologically defeating blows.
Every time this happens, know that you are not broken and you don't have to feel bad about yourself. You don't have to feel guilty about gaining a few pounds back, or about reaching out to food when life gets rough.
Next time your inner critic shows up and you start thinking you can't do it, remember all this is part of your weight loss journey.