You are going to die. Soon. Because your 100 years (if you’re lucky) is microscopic relative to time. And after you die, you will be forgotten (relatively) quickly.
Now, you could despair that your life is so insignificant. Or you could realize that this perspective gives you immense power to live your life.
It doesn’t matter what people think of you. Soon (relatively), everyone you know will be dead and the planet will be populated with people who have never heard of you. What matters is how you live: what you do, who you meet, where you go.
Your mistakes are ultimately inconsequential.
The greatest mistake is living a life of regret.