Getting Older

I just turned 28 years old and if there's one thing I will appreciate as I age it's not having to hear people who are slightly older than me say things like,

"Enjoy your youth, it doesn't stick around forever!"

or

"Oh God, you're so young! I feel ancient!"

or

"Take advantage of the time you have now."

or

"I wish I could be your age again."

Why do these phrases irritate me so much? Is it because I already do cherish every day and whoever is telling me to do so obviously doesn't know me very well? Is it the other person's patronizing tone? Is it because I subscribe to the notion, "you're only as old as you feel" ("only as old as you act?" "Age is a mental state?" What's the stupid notion I subscribe to?). Is it because the person telling me these things is usually only five to ten years older than me? Is it all of the above?