Sad but true fact!
You need to consider that your body is like that of someone else's. Someone that you treasure and that needs to be looked after.
If you nurture your body by taking good care of it, it will usually repay you by making you feel good.
Besides, how can you take care of others if you do not take care of yourself first? Also if you get so sick that you have to be taken care of then someone else will have to be inconvenienced because of you... not to mention it is not pleasant to be sick and can be very expensive. There should be many motivations to take care of yourself if you sit down and think about it.
I exercise and control my blood sugars and manage my diet carefully because I need to stay well to work and take care of my family.
This is a mindset and you need to decide on what you think and how you act.
Its easier to tell.. than do.