I read a saying sometimes ago. "who you are today is a result/product a yesterday's actions."
I think this is a pretty accurate statement. If you are successful today, it means that you have put in a lot of effort yesterday or even the day before to ensure this day.
On the other hand, if you're unhappy about your current self/state today, it also means that you did/didn't do what was necessary to achieve a better you today. As a result, you're unhappy today.
So what does that means? Meaning that if you're not pleased with where you are today, do something about it to make it up for tomorrow.
Simple thing, e.g. your face has become oily, lots of pimples, what do you do? simple, you wash, rinse, scrub, apply pimple gel/treatment, and eat healthier. That's what I did. The pimples won't go away by themselves. Do something about it.
Unhappy about yourself today? Well, do something about it. Today.