Isn't it odd how 29 seems so much younger than 30, and 39 so much younger than 40, and 49 so much younger than 50? I always said that I didn't even feel like a "grown up" until age 24 and a half. Then birthdays seemed to add up in 5s instead of just every 1 year. And you don't really, really feel the concept of what 50 means until about 48 and a half.
But 50 is definitely not a time to feel gloom and doom or to be sad to make it there. It's a time to reflect and stop "spending" time and do more "investing" time into things that make more of a difference to get you where you want to be, if you are not where you want to be at 50--physically, mentally, emotionally, spiritually, financially, and any other -ally you care to be.