How do you become content with yourself, your life

You can always achieve more, do more. At times I feel like I've done really well for myself and other times I feel like I am so far behind in life and really managing life in general poorly. I'm pretty sure I'm on a dead end career trajectory, albeit pays well enough its not anything I had imagined for myself, nor want to be doing five years. I don't see a clear path forward and I'm terrified I've squandered half my life not getting good grades in college, not paying attention in high school. Not starting a career that I can strive to achieve in. I got complacent and lazy letting years go by.

How do you accept where you are at in life without beating yourself up? I look at where I am and how much time I have left and it terrifies me. We get one life to live with no do overs and I'm afraid I have made wrong decisions or refused to make necessary decisions at all.