If you could write a note to your younger self, what would you say in only three words?
I had two thoughts. 1) Words can hurt. 2) Try your best.
What would your note say? 
Slow down kid! You'll get there eventually just enjoy being a kid.
Always have hope! ❤️
Just say no! 
Life is life
Be more responsible
Accept your fate
Be the difference.
Trust your intuition.
Pay it forward.
Choose your values.
Know your surroundings.
Consider the consequences.
Learn body language.
Defend the defenseless.
Learn from animals.
Learn from children.
Consider the alternative.
Plan your future.
Everything in moderation.
Laugh at yourself.
Knowledge is power!
Be an inspiration.
Grow from mistakes.
Be happy anyway.
Don't tolerance oppression.
Seek the truth.
Define your success.
Trust your instincts.
Strength in sensitivity.
Never lose hope.
Sincerity is everything.
Apologize when wrong.
Get over yourself.
Improve your shortcomings.
Have good credit.
Save your money.
Give free hugs.
Don't comprise integrity.
Don't tolerate bullying.
Never stop learning.
Ask God first.
Learn from everyone.
Make yourself laugh.
Be like yourself! 
Be your Bestie! 
@Miawalse these are wonderful and I share similar feelings
Nothing lasts forever
Be more proactive