My eldest daughter will soon be 25. She asked me (and others) about what we would say to our 25 year old selves (if you know what I mean).
Here is one idea (with a couple of PS):
Take every opportunity to learn as much as you can and grow as much as you can. Then, when you are 26, repeat. And when you are 27, repeat again. And when you are 28… (and so on).
PS – get yourself a mentor: someone that you would like to be like when you are their age.
PPS – get a mentor who will help you peer over the edges of the box.