Is life short or not?

How can I view life as being long. I keep thinking of how life is short and always hear people saying it, that it makes me depressed. Is life in reality short, or is it long? Sometimes i think that its actually long but when people reach the ends of their lifes or certain points in their lives, it just seems like its gone by fast because they have made it to the end of their life. But i cant get the thought out of my head that its short and before you know it, its gone! Please explain!