Jon, I get where you're coming from. I'm feeling the same just now about shooting.
When if first got into clays (many years ago) I was mad keen, then got my own gun, then got into game shooting, then got more guns. I was all over it like a rash. I was shooting whenever and wherever I could, and was travelling the country to do so, putting teams of guns together to shoot at any and every opportunity.
Now, I can take it or leave it and in fact I get more enjoyment out of working my dog on a shoot rather than shooting myself.
Its natural for one's tastes to change and evolve. Don't feel bad for letting go of something you used to love. You'll either find your mojo again or you'll move onto something that you find equivalent enjoyment from.
And frankly I don't blame you for finding that red tape sucks the satisfaction out of doing rescue work. It would drive me nuts!