It doesn't matter. I just changed the age for fun. But it can be frustrating when someone discredits you because of age old or young. It mostly is a loss for them in the end though. They're the ones that miss out on a some good advice and new and fresh points of view, but I digress. Back to the topic at hand.
Sorry, bud. Didn't mean to open up a can o' worms. Wait...can o' worms. That's actually on-topic!
I wouldn't worry about credibility issues regarding age. There are 20-year-old punks and there are 40-year-old punks. The opposite is true also. And I'm not giving a guy a pass just cuz he's 50.