There are notable exceptions, within the hobby, that will get you out. Expeditioning, fox hunting (outside), Summits on the Air and I'm sure there are a few others. In fact, and I may be a little biased, I think that the SOTA Goat award is one of the toughest awards in amateur radio. The SOTA Goat is an activator award, you must earn 1,000 activator points with the highest value summit worth 10 points. There are some bonus points available during extreme weather conditions, but suffice it to say you will have to summit at least 100 peaks and operate to earn the award. Normally it takes several years to earn this award and you have to do it on your feet.
However, if you aren't into Summits or other outdoor forms of radio there is device that you can wear on your wrist to motivate you to get up and around. These devices count your steps in a day and depending on the device will nudge you to get up when you have been sitting too long. All of these devices have accompanying apps that will sync with the device to give you statistics on your day including steps and the quality of your sleep. I currently use a device made by Jawbone and although I have a somewhat regular exercise regimen, it reminds and motivates me to keep it up. An extra walk around the block or around the office, if done regularly can make a difference in your overall fitness.
I blogged here several months back about the backpacker mentality of saving ounces in our packs while we were carrying extra pounds on our bodies. Since that blog I have lost ten pounds and signficantly improved my stamina. The higher fitness level we can achieve improves our odds to live long enough to achieve some of our sedentary goals.