Have you read the Rabbit novels by John Updike? If I remember correctly it's Rabbit is Rich that has some great stuff about this feeling and how one's expections from life change over time. There's a very interesting passage somewhere about how when you are young you're always reaching out and expanding but then there comes a time in middle age where you crave simplicitly and yearn to cut out all the superfluous stuff that you've learned doesn't interest you. But that doesn't necessarily mean there's any more clarity about what it is that DOES interest you (that "missing" thing?). My favourite bit from those books comes in Rabbit Redux though: "Days, pale slices between nights, they blend, not exactly alike, transparencies so lightly tinted that only stacked all together do they darken to a fatal shade." That's just brilliant, IMHO, if not altogether uplifting. I'm wittering now. Possibly because I discovered that the thing I was missing was really nice wine.
As Mr C states, bowel movement is critical.......without this, you are literally up **** creek (disagree about the navy blazer, but cream cotton slacks are good, along with a Gabicci collared shirt and ironed handkerchief. Loafers for shoes please). Being challenged, physically and mentally, keeps you in positive shape......even if it is a small challenge, it does you good. And to be honest.....as you get older, money becomes a lower priority, which in its own way, makes your life easier?