Stretching:
My senior year of high school, I actually stretched my dick every morning in the shower. I read online that stretching helped and I wanted to see if it was true or rubbish lol. My biggest thing was I wanted to be above average but I didn't want an anaconda either. I held the stretches for 10 seconds and put in a north, south, east, and west position. I did it everyday until maybe the end of my first semester in college. I found I had grown an inch and half since my senior in high school. It was kind of cool actually.
Losing Size:
I've actually read that guys will actually lose penis size if they aren't actively using their dicks as they age.
Summary:
If you want to keep in maintain a consistent size . . . you got nothing to lose. Penis is like any other muscle why not exercise it on some good pussy anyway.
At the end of the day no guy wants to be too small or too big.
Size of the pussy: Now an interesting quote
"A man can't control his dick size but a woman can control her pussy size."

-by some random guy