When starting a diet or trying to break unhealthy habits stop telling yourself you "can't" have this or you "can't" do that... change your thinking and gain motivation to continue making progress! I have tried to diet and lose weight numerous times and everytime I have I find it so hard to stick to because they are so restrictive. So, instead of telling myself I can't eat certain foods, I remind myself of the rewards of simply cutting back on such indulgenges and allow myself occasional "treats"
Instead of completely cutting out sweets or chips, say to yourself..."if I can keep up my diet this week, I will have one cookie (or whatever it is your heart desires) on Friday evening"... this way you are cutting back while not being super strict on yourself. This will help motivate you keep going