"Researchers find centenarians optimistic, extroverted, positive beliefs help. There is evidence that some become that way later in life." http://www.webmd.com/healthyaging/news/20120530/personality-secrets-to-long-life. Happiness is good at any age, so it is OK to long for longevity.
For me, Jesus brings a peace and harmony to my life. I would like to think that this transfers into a very positive personality. Aging with faith keeps me grounded. When I need to feel His presence I can call Him up Psalm 139.
Aging is a very personal process, but no matter your thoughts, your beliefs must be based in something...try God! He works for me.