How to Live Today?

There are like a million quotes on seizing the moment, and living the present.
And I get it,  those quotes are like super smart, I understand them, How magnificent advice, live today!

What I don't understand is how?
How are we suppose to live today when the ghosts of our past keeps hunting us? When our future seems so uncertain?
How do you enjoy the now, when all your actions seem to take you further down the slippery slope of life?
How do you not let your past affect you when all your past defines you?
How do you stop thinking of the What ifs?
Where can I find the quotes that explain the how's?

How do you Live Today?
Do you ignore the past, and make the same mistakes a million times more?
Do you ignore the consequences of what might happen?

I've tried living in the moment, I've done things ignoring my past, and I've done things ignoring the future. I tried living the Today, and I got burned.

So seriously how do you live the Today to the fullest with out getting hurt?