Being mindful and self-aware has been the biggest gift for me last year (well last couple years really).

Being aware of what is good for you, what is not good for you, having reminders of that within reach all the time. It's what I've called in my latest podcast "my User manual". (I shared the link to my episode on my blog" for those interested to give it a listen).
There are so much difference between knowing something and applying it.
It can really drastically change your life once you apply what you learn and be mindful of what is happening in your mind and body. Everything starts to be a clue that tells you if you're getting closer to your dreamed life or not. :)