The American beach volleyball star says, "Every day, the butterflies are a little bit bigger."
Walsh was at a ribbon-cutting ceremony Thursday for a training centre for U.S. Olympic athletes. She says she gets goosebumps thinking about marching in the opening ceremony Friday night.
Walsh played indoor volleyball at the 2000 Games and won gold medals in Athens in 2004 and Beijing in 2008 with partner Misty May-Treanor.
Walsh Jennings competed in Beijing under her maiden name but is now going by her married name.