You young folks ever wonder why we geezers seem so cheery?  The September Psychological Science explains:

Studies of the negativity bias have demonstrated that negative information has a stronger influence than positive information in a wide range of cognitive domains. At odds with this literature is extensive work now documenting emotional and motivational shifts that result in a positivity effect in older adults. … The present study … suggest[s] that neural reactivity to negative images declines linearly with age, but responding to positive images is surprisingly age invariant across most of the adult life span.

Sure your body will degrade, and perhaps your mind too, but take heart: you won’t mind so much by then.