I am preparing for a TOEFL Exam so please help me.

"We should always make the most out of today because we don´t know what will happen tomorrow"

Do i Agree or disagree?

I completely agree with the last statement, to be positive in daily life could change everything about how we work, how we live and even how we are with other people. If you are focusing on yourself in something bad, you will be thinking just about bad things. This could make you get dissapointed and it could affect your daily performance. But, if you start looking at the good things that occur everyday, you will completely change the way you live. You will be projecting a different kind of energy that other people could feel because you will be happier, funnier, and generally a kinder person. We don't know what will happen tomorrow because nothing is certain, and we can not change the past, but we can focus on what we do can do in the present to change our future, by looking back and looking at our success and thinking differently to give a better effort on tomorrow's tasks.

You're a good writer, keep it up! Be careful with run-on sentences!