Strengthening the mind, need advice

[Popinjay]

So lately I've been trying to read Nietzsche or maybe The Memory Book or even Sklansky on Poker (Razz section). It seems everytime I pick up the book to read 15 minutes later (max) I am sleeping. I want to be able to read continuously and use my mind for a long period of time not this weak 15 minutes crap. Help me 2+2, you're my only hope.