Finding the sort of exersize or physical activity that you can stick to and enjoy is by far the most important thing.
So if walking and jogging is your thing and weight training doesn't sound too fun or you have had problems sticking to it... some ideas to try...
The only way that you will increase your muscle size and strength is to push your muscle beyond what they are used to. So the point of any change to your routine is to stress muscle groups in ways they are not accustomed to.
Try to add some wrist weights or carry dumb bells while you are jogging.
Find a jogging trail that either has some exersize areas built in, or find a place along your current path where you can do some push ups and pull ups.
Take along a jump rope and work in a few minutes.
Add some sit ups, crunches, and maybe some leg lifts, either along the way or at home.
Push ups will work your chest and by changing the distance between where you put your hands you will be able to work on more areas of your chest, and you will touch on your arms as well.
pull ups will work your upper back and again changing the distance between your grip will change the focus.
the jump rope will replicate some of the results you are getting from jogging, but it will help increase your stamina and help with your calves.
And of course the dreaded sit ups and crunches...but in addition to the obvious, abbs is a core muscle group that will help you develop every other area as well...
And if you haven't done these sorts of exersize since high school gym class... start with one...and work up...they are all pretty hard...
I believe with a little work and imagination you can take any activity and build a whole body workout around it.
"Everyone is entitled to their opinions and it is not my job to change their mind." Dali Lama