To those of you that no longer hunt but still consider yourself a duck hunter (as you should) after years of participation, when did you know it was time to call it a career?
Eric,
Not sure I entirely fit your criteria but will share my thoughts.
I would consider myself a "hobbyist" duck hunter at this point in my life (74 yrs old not as spry as I once was). I go when I feel like it. I may plan to hunt the next morning when I go to bed that night. Yet get up at 3am and decide I am no longer in the mood. AND I don't regret not going.
I did that scenario in fact just this morning.
Instead, (after being up from 3am to 5am) I got up for good at 7am. Bicycled one mile to my local library, shared coffee and fried egg/cheese sandwiches with the Wed/Thurs mornings breakfast club.

Followed that up with a 20 mile ride on one of the local bike paths.
The only regret with not going duck hunting, is that my dog did not get to go duck hunting.
When I was younger, I was pretty hard core regardless of the weather, the success or lack of success. I'd be the very 1st one at the boat ramp. (still am most of the time) Come back to the ramp, with the decoys (and myself,) covered in a film of ice. I once had the local police call my home to ask my wife, If I made it home the previous day. They had observed my rig sitting in the parking lot in the wee hours of the morning, figured no one would have been crazy enough to actually launch in the weather that morning and concluded that I most likely never made it home the previous day.
Yep, my wife said, I was just crazy enough to go out in such circumstances.
I guess I have reached the point I have nothing to prove. I go when I feel inclined to go, don't feel bad about the investment sitting (unused) when I don't go. This was a gradual change but only over about a 2 to 3 year period. I have other hobbies which are in the same category. For a time period I pursued them relentlessly. Now they all share my time, as I am so inclined.
I think my biggest hobby now, is "freedom". It is wonderful to not feel an "obligation" to pursue any one thing. Not that there is anything wrong with the person who has only one hobby. What ever trips your trigger.
I don't think there will ever be a time when I call it "quits". As long as I have the storage space for the equipment and I am physically able to get out, there is the possibility I will go duck hunting.
On the other hand;
One of my previous hobbies was archery. I lived and breathed archery. Spending 4 hours a day, 4-5 days a week at the range and 3 weekends a month shooting tournaments. My wife pointed out, my girls were growing up without me. Cold turkey, I quit everything about archery tournaments and practice for tournaments, except for the hunting side of my archery. I bow hunted 4 different states, for deer every year. That continued up until the time I could no longer physically participate. I went several years not hunting with a bow. Then I adapted by taking up a crossbow. I adapted my hunting style and once again I am bowhunting locally, for deer and turkey.
Now days, I may go bow hunt, I may go ride a bike, I may go fishing, or I may go duck hunting, or I may just do some woodworking. I never am 100% sure what it is I am doing, until I walk out the door.
The other day my wife asked me, "what are you doing today?"
I replied, "this morning I don't think I will do anything. Around noon I'll fix some lunch and maybe take a nap. This afternoon, I'll finish what I started this morning."
Hope you enjoyed my rambling.