how to change the transmission fluid?

There is a Lifetime fluid in the transmission which does nor required regular service, however I'd suggest to replace it - including the filter also- at no more than 100K miles. "Lifetime" fluid is relative. What is the lifetime of the transmission? When it's stop working, right? Of course no fluid replacement necessary for a non-working transmission, which means the fluid really lasted to the life of the transmission. Should be the life of the tranny doubled or tripled by replacing the ATF? Probably, but now it's too hard to tell. It's kind of saying: "Here is a sandwich, and you won't need to eat anymore till the rest of your life." It could be a true statement, because sure as hell you will die without proper nutrition, but would you risk it? Zee