I was matzliach on the 90 day journey and this is what I realized:
1) I must stay busy
2) I have to wholeheartedly want to complete the 90 day journey
3) I must learn every day
I stick with the daf yomi in particular. It brings help from the shchinah, which is the key of fighting the yetzer hara. Also, there's an inyan of starting a new hobby, and learning on a daily basis helps fill in the gap of acting-out for the better.
Also, it's considered doing Tshuva, because when we act out, the thought/imagination of the zera comes from the core with in our mind. And ke-neged that, we use the core of our minds to break our heads to learn Gemara, which is part of our tshuva journey.
Also, it helps to wake up our neurons in our mind to become people who are able to think.
4) Reading the daily Chizuk list that GYE offers helps a lot