Life experiences are most memorable because they define who you are and give you the courage to face your future. You may not know it now, however, looking back you will see how some of those defining moments really built the foundation that shaped who you are. 

You have the most incredible experience ahead of you. Right now, you’re probably feeling a little unsure of the direction that you want to take and perhaps also feeling a bit out of your depth. That’s OK. Have faith in your ability to find the right path and most importantly, believe all those people who tell you that you’re doing just fine -– because you are.

Yes things are tough, and they will get tougher. But so will you. I just wanted you to know that just because you have a math teacher who is an idiot and who is a sexist ass and who somehow can't do math doesn't mean you aren't great at math. You are.

Your life will be a rainbow of colors, with a rich set of experiences, a little bumpy at times, with people that will help you reach for the stars and be the wind beneath your wings. Then one day, you will realize that you create the wind beneath your wings with your positive attitude, your quest for knowledge and understanding, your values, your hard work, your respect for people and what they do, and with the support and guidance of the friends, family and trusted mentors in your life.

You have a lot of potential and many opportunities to demonstrate your capabilities. 
Sometime you may encounter the obstacles or problems which you cannot quickly solve. 
I would suggest that you look at the obstacle as an opportunity. You need to roll up your sleeves and actively work to resolve the issues and achieve what I know you can.