I always though I was average sized based on things like Penthouse Forum, where every guy was 8 inches or more. In porn, there were many sizes represents way back then (pre VHS and pre Internet!) but I still thought I was maybe on the large size of average.
I started to believe that maybe I was well endowed when I started having sex, and the women I was with complemented me on my size. After a few different women all basically call you well hung, you tend to believe them! Then I saw multiple Penis Size Survey results when they were first published on the web, which confirmed that my 7" by 6" (nbp) was indeed on the higher side.
Has it affected my life in any way? Only when I first get naked with a new woman. Knowing that those women who like the 'filled up' feeling would not be disappointed gave me some sexual confidence.
But, having a big dick does not make you a good lover! Being a good lover is paying attention to what the woman you are with likes, how she responds, and ensuring that you are doing everything in a way that maximizes her enjoyment. While most women have made remarks about my dick, the best compliments were those made post orgasm, when she expresses how good that sexual session was.