My mother never made it to fifty. She passed a few days before she turned 45. I am not there yet, but will be soon (a few short years). What would I do differently if I only had till then? I guess a big thing is, I would stop sweating the small stuff. Being discontent. Just enjoy each day. Be kinder and less self-absorbed.
And if I am spared to see fifty, I will plan a holiday. And then enjoy it!