Let me offer this illustration. A man wakes up every morning to spider webs in the corner. Day in and day out, he sweeps out the webs. One morning, he wakes up to the realization, “why don't I just kill the spider?”
That's what sanctification is about. It is an instantaneous realization that the way that you have been living your life has been ok but that there is a better way. Sanctification is a change of your intent. Sanctification is God killing that selfish part of you, setting you aside for His purposes, no longer living for yourself.
Sanctification is a crisis experience but one that grows. Even though he may have killed the spider, he needs to kill any other spiders that move in or other spider webs will appear. This is congruent with the teaching of "work out your salvation with fear and trembling." Now, you say, "that leads to a danger of a works based salvation." However, James says that faith without works is dead. In Nehemiah, he told them to work and pray while they built the wall. A proper understanding of sanctification realizes that any good that a Christian does is only done through the power of the Holy Spirit.
This crisis experience of sanctification is a change of the intent of the heart. God takes that heart that is bent towards self and sin and turns it to pleasing Him, much like your son who is getting you a drink of water. He wanted to please you rather than himself.
In my life, I was saved at six by my mother's aid. At age 17, I was in Las Vegas and watched a man put money into a slot machine. He looked so sad. I remember God distinctly telling me, “do you want a happy Christian life or a sad one?” That was my sanctification experience. That evening, all alone, I prayed that God would use me however he wanted and that I would never turn my back on him. My life after 17 was much different than it was before.
I have had experiences where I hear Satan's voice, “see? All that Christian stuff isn't worth the trouble. Just give it up!” When that happens, I am able, with the help of the Holy Spirit, to remind myself that I had a sanctification experience where I vowed I would never give up on my relationship with God.
My sanctification is entire because not only do I have all of the Holy Spirit (His Spirit is given without measure) but He has all of me as well! This sanctification is exhibited by the FRUIT of the Holy Spirit. That means once I became sanctified, I received all of the fruit but it was not fully mature at that point. My sanctification needs to continue to grow. The different fruit may grow at different rates but it is all there. My goal, with God's help, is to have all the fruit mature in my life.
So, I still sin. But when I do, I have an Advocate with the Father. I stop, confess, and move on. I don't beat myself up nor allow Satan to drag me down. The closer I stay to God's Holy Spirit, the shorter my fall when I sin.
Now you know what to do. What are you gonna do?
While you're deciding, that spider is building more webs...
BE A MAN.