Welcome to the forum!

The books, in addition to forum reading will both help, in all likelihood. I thin immersing yourself in the idea of a lucid dream can be one of the greatest things you can do, next to keeping up with a dream journal. I know you said you lack discipline but perhaps the goal of a lucid dream will help with that.

As for a mantra...it need not be related to lucid dreaming if you don't want it to be. The mantra is designed to help you set your intention and retain the thought/goal while you are dreaming. The mantra should be significant to you and can be as simple as "Lucid" or "Giraffe". What's important is that you recognize it(the word or phrase) and that the mantra helps you achieve lucidity.

You need not say the mantra out loud if you wish. I never do. But do try taking some time to relax during the day, particularly if you feel run-down or tired in the afternoon. The sleepy periods are good times to relax and do your mantra and cement the word/phrase into your mind. Right before bed is alright but don't lose sleep over it, and realize that you're not likely to have luck with dreaming until after several hours have passed. If you wake up in the night (naturally or for WBTB with alarm) try also reciting your mantra then.

We have these great people on the forum called Dream Guides. We selected them for their experience and ability to help people and they can help you reach your goals. You may post your questions as a thread on the forum or you can send a Private Message to any of the Dream Guides for help.

Pleasant dreams! Enjoy the forum!