At first it will seem next to impossible. You will feel antsy and be unable to focus. You will barely be able to stifle your yawns. You won't be able to wrap your mind around a simple piece of shaklah ve'taryah. But rejoice. That is the perfect raw material to work with. The tumah toxins inside you are screaming against the powerful chemo treatment of the "samah de'chaya" - the elixir of life. Focus, focus, focus. Drag yourself through the Gemara, then Rashi, then Tosefos, then Maharsha. One hour. Two hours. Be brutal with yourself. No quick fixes of "acharonishe torahs". Memorize the shakla vetaryah. Think through it backwards, then forwards. Try to find flaws in the breathtakingly beautiful logic.
Do not learn the way you learnt way back when, in yeshiva or kollel, lackadaisically looking for the quick chidush fix. Learn with total and absolute focus, as if you are trying to decode the secret key to a million dollars. Let the sweat gather under your armpits and let a tingling feeling run down your spine, as you slowly, ponderously, with great effort, unlock the strands of Divine DNA within you and within the Gemara. Do this night after night and early morning after early morning. Write down you questions. Take them to your local Rosh Yeshiva.
Consider the "drip-drip" of this daily regimen to be a vital part of your treatment. Know that it is building up your antibodies in small but steady increments and restoring your health. After a while, compare before and after photos of yourself. Before: dead eyes, forced smile, deep sadness. After: twinkling eyes, warmth, attractiveness. Rejoice.
Your yetzer horah will still attack you, and he is guaranteed to continue to do so till your very last breath, but almost immediately you will begin to notice the following:
1. Extremes that at one time glittered, now seem repulsive. They no longer interest you. You cannot imagine how you once embraced certain sewage up to your eyeballs.
2. The frequency that you fall will diminish. You will finally get a life outside your two-dimensional self-made gehinnom. You will feel and exhibit genuine warmth for your family and community.
Hashem has sent us an extraordinary blessing, the mp3 player. Switch off, for good, that radio in your car and in your home. Wash your ears and starving mind with the beautiful sound of shiurim, downloaded to your mp3 player. Many times, especially when you are driving, you will not be able to focus on a shiur, but background noise is also fine because you will still be living in the Beis Hamedrash. You will be steadily rising, not sinking. Find a maggid shiur who speaks to your heart, who resonates emotionally, whose neshama resides in a holy place. Mix upbeat and non-threatening halacha shiurium with uplifting hashkafa and mussar.
And here is a very important tip: Say c"v your yetzer horah gets the better of you; you fall and go somewhere you shouldn't. There is no reason to sin on the way there and back. What a bitul zman! Listen to a Torah tape. Farkert! Show the yetzer horah that bit by bit you are taking over. You are on your way to winning, and winning big.
Chazak VeYe'ematz!