Your heart pumps blood down to your legs easily. Gravity does most of the work.
Getting it back up is a completely different problem.
Blood and fluid have to travel from your feet and ankles all the way back up to your heart, against gravity. Your heart alone does not have enough force to do that job properly. So your body built a second pump to help.
It lives in your calf muscle.
Every time your calf muscle squeezes and releases, it pushes blood and fluid upward toward your heart. Researchers have called it the calf muscle pump for decades. Some call it the second heart, because that is essentially what it does.
When it is working properly, fluid keeps moving. Your legs stay light.
Now here is what nobody told me.
After around 50, the calf muscle naturally loses some of its strength. It does not squeeze as hard. The pump gets weaker. And when you go from a working life that kept you moving all day to a retirement with far more sitting, the pump barely activates at all.
Every hour you spend sitting, your calf muscle is almost completely still. Nothing is pushing the fluid in your lower legs back upward. It pools. It builds. By mid-afternoon your ankles are swollen and your legs feel like lead.
The compression stockings were squeezing fluid upward from the outside. That is why they helped while I wore them. But the moment I took them off, the pump was still weak, and the fluid started pooling again within hours.
I had not been solving the problem. I had been managing the symptom while the real cause kept going underneath.
Once I understood that, three years of almost-working solutions suddenly made complete sense. Of course they did not hold. None of them were doing anything about what was actually happening inside my leg.