There's another element to it, which is looking at the wealth balances and then measuring that against the proverbial "sand through the hourglass" of life, regularly reminding you of it.
But on becoming a spender vs. an acquirer, do you think it's more about not compiling more wealth on a monthly basis, or that your days won't consist of "going out to kill something" each day, and having that rewarding sense of accomplishment/contribution like you've done for decades now? My stepfather has struggled mightily with that concept.
I'd say when the time comes, give it a few months to sleep in and chill, then find something else that gets you going whenever you feel the urge. Teach a class, coach some kids, maybe get a certification in wealth planning or something to help others get after their goals.