It's called the law of diminishing marginal utility. Each fish you catch will have less and less value to you. What has happened to you is that you've reached the point where catching another fish is less valuable to you than playing with the dogs or staying warm inside.
When I get like this I look to change things up or to give myself other goal/objective/challenges.
This can take on many forms such as, spending the entire day fishing a new technique (fly fishing, swinging spoons), fishing entirely new water that you've never been to before or never had success on, capturing fish for the brood stock program, fishing only big fish water in an attempt to find a derby winner, taking someone new out fishing and gettting them into their first ever fish (with the way you've been posting I'm sure you wouldn't have a hard time finding people wanting to take you up on that one).