Activating the Now

A month or so ago i was listening to the Power of Now book by Eckart Tolle. I was interested yet kind of apprehensive by this new way of thinking. And then by the time i listened to the very end of the book i couldn't remember why or how to live in the now. I couldn't remember how to do it.
So i started to listen to it again and pay closer attention. Its kind of scary thinking the "pain body" as a creature feeding off of you.
I have have a tons of guilt, for what i have no idea, and now i realize it was my past, and most of my stress comes from the future. I don't see things in a" different light" per say say like the man's voice stated about the tree. i hope to some day. i believe i have been living in the now all day today, stress about fiances came up and i didn't get a sick anxiety. The only thing that i wonder is how much in the now do you have to stay. If you think of all the things you have to do today and how you have to do them isn't nessaryly in the now. How far can think ahead, ect before it is not in the now? im sure talking about thinking about the future isn't in the now. but that was just one thing that came into my head while trying to stay in the now. i think this will be a great and the most useful practic for me. i have also been having a small physical pain (craps and when i do not dewell on it i just stop and think of now.....(its hard to explain) the pain disapates