I agree that looking through old photos can make you feel mournful, remembering your past life and thinking of happy youthful days which are now long gone. But I think their value is more for future generations, who will look at them in amazement. Did grandma actually look like that, long blonde hair and a mini skirt?
I really think that photos and videos come into their own with the passing of time, and the longer the better. Therefore keep your photos safely and treasure them. Most importantly, write on the back names, dates and places otherwise in the future you will be 'strangers in a box'. I have lots of photos of ancestors from 50-150 years ago and they are fascinating, but one album turned up full of beautiful Victorian family photos and no-one had a clue who most of them were which is really sad.