Great points. Another consideration could also be whether you still want to work at UPS, or would prefer to get a different gig to ride into the golden years.
If you got say, a $15 an hour job, and there are lots now and more coming as minimum wage increases in some states, you could strike a happy medium.
$15 x 40 x 52 = $31,200.
+$3735 X 12 = $44,820
= $76,020
That's like being paid for a dream 8.0 hour dispatch every day, as long as you want to work.
Let's say you're a driver, today, making $36.
$36 X 40 X 52 = $74,880.
Of course there's still medical and other bennies that make the comparison somewhat unfair. Still, if you really want out, and you have the qualifications, it's another set of numbers to consider.