For better or worse the way you are now is a summation of all of your past choices. There's no escaping it. You are responsible for you.
You've chosen your career. You've chosen your partner. You've chosen the foods you eat and the movements you engage in. In fact you choose your mood too. As embodied cognition shows us, your actions can influence your feelings. Want to be happier? Choose to act happy.
Of course you could choose not to change a thing. To stay on the default path of life. But is that a choice to live or to be alive?
This is far from doom and gloom.
What this means is that now--in this second--you can choose to change. You can opt for growth instead of decay. You can choose possibility over routine.
A word of caution: your perception of the world may limit what you think are valid choices. But the map is not the territory. What is you see is not what is. The rules that you play by are subject to change, and when they do, you'll find that you can choose far more than you thought. Open the box a bit, and you'll find that you have many more options than you thought.