Where do I start when my work queue is completely full?

A full queue can freeze you before you even begin. You look at all of it at once, and the size of it makes every task feel equally urgent, so you touch none of them. That is not laziness. It is your mind overloaded by trying to hold the whole pile at the same time. You do not have to solve the queue. You only have to pick the next one thing. The oldest, the most urgent, or just the one nearest the top, it matters less than you think. Starting anything breaks the freeze, because motion is easier to continue than to begin. So do this now. Choose one item, ignore the rest, and finish just that. Then choose the next. The queue shrinks one piece at a time, and that is the only way it ever gets smaller.