…in my opinion
Is your expression. Nothing is more pleasing to look at than a pleasant expression. Nothing wins people over so immediately as a kind natural face. Don’t look forbidding… smile… not an ingratiating or a servile smile, just a ‘pleased to see you’ smile. Be a happy person; don’t frighten people before they’ve even come into your personal space.
If you worry too much you will never look young, because worry marks your face. You have to learn not to ‘wear’ your personal problems, because what you think, ultimately affects your expression.
You can’t, I suppose, change your thinking any more than you can change your circumstances, the only thing you can change is your point of view. That’s something you can practice.
For example, if you want something but can’t afford it, the thing to do is to think of how you can get what you think you want as if money were no object. Write it down, prune it and accept it as a possibility, then you can have anything you want. My ideal though is not to want anything, I’m not a ‘wanter’, I’ve always been like that and life has been very good to me.