Before I had a real relationship with Jesus I thought the only way to get to Heaven was through my good works.
I thought the only way I could get to heaven was to get to the point where I never sinned at all.
Then I realized that I could never achieved that mark, and that through Jesus was the only way that I could get in.
Now I know that Jesus work on the cross was all I need to be accepted by God.
When I sin now, I as for forgiveness, and repent of my sins. I now have the assurance of knowing the Jesus covered all of my sins on the cross, and unlike "insurance" like you would have on a car, I can't lose it.
I now fully and completely rely on Christ's work on the cross, and my trusting in that is all I need to go to Heaven.