Thats about 10 pounds for non-metric speakers. This is pretty much a useless item, as I've frequently pointed out. Fixed-weight dumbbells like this are meant for gyms where they can have a whole bunch of them in progressive weights so you can just grab what's appropriate. If that's all you have is the one set....Then they are going to very rapidly become too light to do you any good. And... Ignore the idea of "jogging" with such weights, they are too heavy for that. Save up your pennies and buy a nice, basic adjustable barbell/dumbbell set. You can get this new for under 100 bucks. If you shop thrift stores or craigslist, you can probably get them a lot cheaper. For all weight-lifting exercises, you want to use a weight that you can handle for 10-12 repetitions, with the last couple being hard to complete. Now, you can walk or do aerobic exercise with hand weights; that's called the "Heavyhands" system. But you need much lighter weights for that. About 2 pounds to start.
You can tone up and build endurance but you won't build muscle with those weights.
Jog with them and use them for tricep and bicep exercises for high reps. They are the same size as the dumbells I used at your age and I made some considerable gains.
lifting any weight will do something if you lift it enough. small weights for tone. Large weight for big bulky muscles.
