I think it's built in, instinct.
If you watch hunting dogs, and they are bred to express hunting instinct, once they lock on to prey everything changes. Intensity, attitude, and so forth. And for upland game pure joy after a retrieve.
I find myself doing likewise with the immediate prospect of shooting game or hooking a fish. Focus locks on, the quality of the day, whether or not I feel cold, and other things irrelevant to the task at hand disappear. Senses sharpen. The mind quickens to find my best advantage. And I simply feel wonderful when I succeed.
Sharing the day with friends, enjoying nature, watching a good dog work, being part of the ecosystem rather than a mere observer, are all secondary benefits and great they are. But I believe it's that inexplicable desire to get out in the field that leads to the rest.
And this is probably an unpopular opinion, more so among those that don't experience it. We naturally don't like the thought of being manipulated by some unexplainable urge. It's an affront to rationality, an insult to the intellect. But of course unlike lesser animals we can control our instincts and direct them to good purposes. Like enjoying the day in the field with friends, family and dogs. And obtaining delicious provisions for the freezer.
