Word of advice to drivers who think this job is the only exercise you need. I am a 48 year old full time driver (started part time in 87 went full time in 93). This job will cause you you to over work many parts of your body and ignore other ones. A few years ago I decided to hire a personal trainer. It was one of the best decisions I ever made. She focused on building strength in my core and balance along with total body. My goal is not to be ripped but to be fit. It has made my job a lot easier. I now work out 3 days a week before work and once on the weekend. I am now very in toned with my body. I have learned to engage my core to help with back and hip pain and how to be more efficient with my muscles.
The most important thing in my opinion is to have a strong core with this job.