It is great to have a growth mindset! Once you start to develop this mindest it is easy to fall into the trap of taking on too many things and trying to get good at everything. This is fun but if you want to be great or a master then you cannot spread yourself thin. There is only 24 hrs in a day and for you to be a master you have to focus on one thing.
To learn more about this concept read The One Things by Gary KellerThe ONE Thing: The Surprisingly Simple Truth Behind Extraordinary Results