Need some inspiration? Take some from Fauja Singh, a 101-year-old Indian man who ran a 10K in Hong Kong over the weekend. He finished the 10-kilometer run in one hour, 32 minutes, 28 seconds. He’s hanging up his running shoes after this, but he might as well, because he’s most likely the oldest person to ever finish a race this long. No topping that.
EDIT: Modified to note that he ran a 10K, not a marathon. Sorry about that.