I have noticed that my perception of time changes with each half-decade. Suddenly I find yourself saying things like, "Where does the time go?" or "What year did we do that epically unforgettable trip that changed our lives?" Time moves incrementally faster as you get older and that drastically changes the perspective as a result. Suddenly a year is an insignificant amount of time. Instead of, "Wow! That was already a whole year ago?" it's not "Oh, well that was only last year so it basically just happened."
When you are a kid, you have no sense of the longevity of life. Your entire life IS what is happening right now and "the future" means tomorrow or the end of the week if you're really ahead of the game. Graduating another year in school was exciting and the only anxiety you felt embarking upon a new year was picking out your first day of school outfit or freaking out over the fact that you're starting yet ANOTHER grade with a full set of braces. Fast forward, now you think in terms of decades and their associated deadlines. Every year has expectations attached to it - whether it's job pressure, relationship milestones, a biological time clock ticking, etc. - so each passing year whizzes by while you tirelessly try to keep ahead of the currant. Your definition of the present is probably more like anything that falls within this calendar year, and the future is synonymous with retirement.
I challenge myself to stay present in the ACTUAL present. When an entire week goes by without something memorable associated with it, it's time to sign up for a meditation class or search the other meetup.com groups in your zip code. I can assure you, a solid hour of sitting in silence will make very aware of each and every passing minute.