rosie-it IS better late than never. Making changes, even now, could affect how well you age. Statistically speaking, many of us these days will live to our 90's but how healthy we are when we get there is in large part due to our health habits during our life.
Besides that, in our younger years, our bodies can still recover from misuse-like too much junk food or no exercise-and keep on going. As we get older, in our 50's and 60's, sometimes even younger, the accumulation of years of bad living shows up and our bodies can't recover naturally anymore.