Advice Monday: What would you tell 21 year old you?

Remember a few weeks ago when I wrote a letter to myself on the first day of school? I read so many touching and inspiring comments that I wanted to expand on it. I know most of my readers are either my age or older and I want to soak up as much knowledge as I can. I’ve decided that every Monday I am going to start asking questions that are on my mind about growing up, college, etc. 

 If you had to tell me one (or two) things you wished you knew when were you 21, what would be? I’m serious, I want to know thee things so I can learn and start doing them in my own life. 

I have this obsession with making sure I appreciate where I am and what age I am. I am so paranoid that I will wake up in 9 years and be 30 and wasted my 20’s and was a nasty person ,etc.