How do you get the years back?

I read and I understand less. I have subscriptions to Harper's, The Sun, and Lapham's Quarterly. Increasingly I am confused rather than edified. Around me I see kids nearly young enough to be my children acting with a perspective and a wit and an intellectual rigor I dont possess any longer. Or I wonder did I ever? If it is not a regression then it is delusion and stasis and areested development. I had a raging meltdown in a Ford dealership 2 months ago because I was looking to buy a Ford Ranger and felt I was being treated dismissively by the salesman and with blatant contempt. I had enough of my wits about me to shout as I was continually exiting. But it occurs to me that if at my age I can't navigate something as routine as the purchase of a truck I may be in very serious trouble. Is there any way I can get the years back so I can properly accrue perspective and character?

Ever have your Vitamin D level checked?