The ideal fitness program for those over 35 is 2-3 days of an hour of varied, intense resistance work and 2-3 days of 25-40 minutes of focused cardio/endurance work. That's all it takes. This will keep you going strong and looking good until everything finally breaks down and you throw in the towel on vigorous life and write your wills, get a trust and estates lawyer, and set things up to await the grim reaper.
Plus, of course, your usual sports activities and Yoga, shopping, work, hiking, jogging, casual bicycling, swimming, sex, whatever which are fun but of no health benefit. (People with physical jobs don't necessarily need this stuff.)
We mentioned in the past that, except for the elderly (over 78-80 in the US these days) or those with serious cardiac or pulmonary problems, walking, fast walking, comfortable elliptical or biking, do nothing at all to improve fitness or to burn fat. For the otherwise healthy, I consider those to be little more than anorectic rituals or wholesome entertainment.
Cardio can be boring as heck. My cardio exercises use intervals to keep it interesting. Here's an interval program that even cardio-hating people can stick with because it mixes variety with challenges: A Way to Get Fit and Also Have Fun:
The essentials of 10-20-30 training are simple. Run, ride or perhaps row on a rowing machine gently for 30 seconds, accelerate to a moderate pace for 20 seconds, then sprint as hard as you can for 10 seconds. (It should be called 30-20-10 training, obviously, but that is not as catchy.) Repeat.
Their research showed that many do not stick with a prescribed program, making it all useless. Lazy does not work. To add interest, I rotate this sort of thing from bike to elliptical to rower with minimal rest in between. Depending on my free time, I quit it all after 30-40 minutes.