I would have suggested not buying GTD, but guess I'm too late
Reasons are the basic principles can be learned in minutes, like most other 'self help' things it's padded out to fit a book so it can be sold.
The irony being reading a book about defeating procrastination is just...procrastinating.
As has already been mentioned, mtf'upping, self discipline are key, everything else is just trying to avoid the pain.
I use trello for everything, with application of some gtd techniques, and if I'm really busy, use a task timer app in chrome.
Temptation is to run off making task lists, this is often self defeating as it'll depress you and you'll be back to procrastinating.
Keep the lists small! And list the things you have completed, this will give you that warm fuzzy at the end of the day.
Saying no is a great skill to learn, and one I'm still struggling with.
As is rolling back the insidious email culture. As has been said already, I dump CC's, and directly addressed emails I deal with the next day (they don't leap to the top of my to'do list ever). If it's urgent, speak to me.