I heard this quote ample times in my life. But I have another opinion. success is not perceived with the same definition by everyone. First define what success is for you.
If being independent financially is success to you, work hard to get a good job (job in the sense an actual job or your are business). This is success.
Marry that long term gf/bf, now you will lead a stable family life. This is success.
Raise you kids well, they will mirror you in some ways. You feel proud. This is success.
Now these are just common in everyone’s life. These three will define you every day. These are something you face almost every day. If you tackle these things, you are way ahead on the road to success.
Here everything takes significant amount of time to take a shape. They are worth your time.
If you want to do it early the:
Take you decision carefully when you choose your career path. You can always switch paths but it will take time.
Maintain peace with yourself. You will be mentally strong and it is a great asset.
If you have a self-doubt before taking up on big projects, give it a shot for a week. You will know it yourself.
Don’t waste your prime years sitting at home.