"Dentro de veinte años estarás más decepcionado por las cosas que no hiciste que por las que sí hiciste."

Simplified Meaning:

Imagine you are thinking about what your life will be like when you are much older. People often regret not taking chances or trying new things more than they regret making mistakes or failing at something. For example, if you always wanted to travel to a new country but never did because you were afraid or thought it was too difficult, you might look back and wish you had just gone for it. It's better to try and discover new experiences, even if they don't always go perfectly, rather than always playing it safe and wondering what might have happened if you had taken that leap. So, it's good to take risks and follow your dreams now, because in the future, you'll value those experiences and adventures.