Why do I procrastinate on things I actually want to do?
The short answer Because the resistance is information, not a defect—and you haven't read it yet. Procrastination on a thing you genuinely want is usually the body negotiating a real threshold: the work is exposing, or hard, or matters enough to be frightening, and the reluctance is your honest measure of that, not laziness. Forcing a belly-flop and walking away are both ways of refusing to read it. The way in is to trust that the reluctance is telling the truth about the water, and enter by it.
The longer answer
You came to swim. You want to swim—you've thought about it all week, the cold clean shock of it, how good you'll feel after. And now you're standing at the edge of the pond in the grey morning, and you are not getting in. You dip a toe. You wade to the shins and stop. You find, absurdly, that you'd rather stand here in the cold air being cold than get into the cold water you came for. Anyone watching would swear you didn't want to swim at all.
But you do. That's the thing worth noticing—the wanting is real and the not-doing is real, and they aren't a contradiction. The reluctance isn't the opposite of the desire; it's the body doing an honest survey of a genuine threshold. The water really is cold. The shock really is a shock. Your reluctance is not weakness; it's an accurate report about the size of the step, delivered by the part of you that has to actually take it.
Most of what we call procrastination is this—standing at the pond. The thing put off is rarely a thing unwanted; it's a thing whose cost the body can feel and the plan could not. The essay you can't start, the call you keep not making, the work that matters most and moves slowest—you circle them the way you circle cold water, and then you name yourself lazy, which is exactly the wrong reading. You're not lazy. You're at the edge of something real, and you can feel it.
And there are only ever two false answers at the pond. One is the belly-flop: force yourself in by violence, override the report, and pay for it in a shock you needn't have taken so hard. The other is to dress and go home and decide you never really wanted to swim. The true answer is the third: read the reluctance as accurate, and enter by it—to the waist, breathe, then under, at the pace the cold will actually allow. The reluctance was never telling you not to swim. It was telling you the truth about the water, so you could get in without lying to yourself about how cold it is.
Whether, once you're under, it's as good as you'd hoped, I can't promise; some ponds are just cold. But you'll not have got there by pretending the water was warm. It may be so. It may not.