Right, I was lucky that I never hurt my back, knees, shoulder, etc. like so many of my co-workers did. I was, however, diagnosed with prostate cancer 6 months before I got out. Luckily, it was early and I had it taken out. Two years later, I'm feeling great with no signs of cancer. If I wouldn't have had the routine physical with a PSA blood test, maybe I wouldn't be around to enjoy any of my retirement. I was perfectly healthy and never sick in my life.
My point is, that you never know how much time you have and you have to enjoy life if you have the finances to do so. You could get a disease or get hit by a car tomorrow. Don't spend 60% of your day at UPS longer than you have to. I missed much of my kids growing up because of long hours so I didn't feel bad at getting out at 50 1/2 and enjoying life. If you don't have hobbies, get some or travel. Unless you're in management, there is more to life than UPS.