Here is the good news, right up front.
If you were vested, your pension is yours. You leave, you take a new job, you move three states away, and that pension still owes you money. Your former employer cannot take it back because you quit, because you got laid off, or because your boss did not like you.
That is federal law, not company policy.
Now here is the part nobody warns you about.
The day you walk out, your pension quietly stops growing. Not just the contributions. The formula stops. And because most private pensions have no cost of living adjustment, that frozen number starts losing purchasing power immediately and keeps losing it every year until you finally claim it.
A pension you earned at 45 and claim at 65 is worth a fraction of what it looks like on paper.
So the pension survives. It just goes to sleep, and it wakes up smaller than you expected. Let's go through exactly what happens, what you control, and the mistakes that cost people the most.