According to the text above, Colin looks and behaves as if he were ...

          The aging process affects us all at different rates. Some people of fifty-three, like the esteemed author, look a mere thirty-five, with sparkling brown eyes, a handsome gait and the virility of a steam train. Others, like the author’s friend Colin, look like little middle-aged men at twenty-one with middle-aged outlooks of set ways and planned futures. In women the former condition is common but women rarely suffer from the latter, being fired with the insatiable drive of ambition for either an independent and distinguished career in a still male-dominated world, or a home and seven children by the time they are thirty followed by an independent and distinguished career as a Cheltenham councillor or a public relations agent for Jonathan Cape, in later life.
         No such luck for Charles Charlesworth, who was born on the 14th of March, 1829, in Stafford. At the age of four Charles had a beard and was sexually active.
         In the final three years of his life his skin wrinkled, he developed varicose veins, shortness of breath, grey hair, senile dementia and incontinence. Some time in his seventh year he fainted and never gained consciousness
         The coroner returned a verdict of natural causes due to old age.

Hugh Cory. Advanced writing with english in use. Oxford University Press, p. 34.