Basically you know that gaining weight is bad, but you want to be more tolerant about it in yourself? Dieting and a lifestyle are different things. You can simply start eating healthier and sometimes give yourself a break and eat what you feel like, as long as it's not excessive. Some diets are too harsh, but you can do important things to reduce weight that don't take much effort, like not eating before you sleep and avoid sugars. As per dealing with weight gain, you don't have to give it that much importance, but if it is bothering you a lot, you can tell yourself that you will change that soon and it's just temporary, or actually make a plan to do it and solve the problem.