How do you resist when you want something that isn’t so healthy?

I try to think that the thing I really want isn't actually helpful for me and in the long term is in fact going to hurt me.

For me, when I want some unhealthy food for example, I tend to prepare a healthy meal anyways and then eat it, even if I really want the other food. After, I find myself not hungry anymore, and the food I ate tasted as good as the unhealthy one, cause simply I was just hungry. I guess it applies in ways with other unhealthy things.

I don't. The key to eating healthy isn't completely giving up on junk food and things we like. Instead, try filling up on all sorts of healthy food. You can still have the 'not so healthy' food every once in a while. As long as you keep exercising, drinking water, sleeping well and filling up on that healthy food, you'll be fine.