You have a busy schedule: work, home, kids, etc., but you need to exercise. What you need is a short workout routine. After all, some work out is better than none. With 15 min a day you may have some benefits from short work outs.
Just 15 minutes of cardio is better than none. You can do it at home so you do not have to waist time driving to the gym or walking to the park. You can train at home, sprint in your backyard or even simulate a 15 minute walk inside your home. If you have a second floor, try going up and down your stairs and you will see what a wonderful 15 minute work out that is. You can also do some running around the house combined with pus-ups and some abs. All in 15 minutes.
If you decide to do cardio by walking around your neighborhood, pick a direction and walk for 8 minutes. As soon as your watch says you have walked 8 minutes go back home. You still have another 8 minutes of cardio.
Weight Training at Home
A cheap set of weights can be stored at home in your garage or in a closet. Perhaps you already have some weight. DO short work outs with these. Even if you do not have weights you can do weight training at home. Try to lift a 5 pound flour bag a few times over your head and you will see how you arm muscles are working out.
Use your body for weight training. Why not? After all you have some weight in your body. If you do a push-up and weight 150 pounds you will have to lift that weight from the floor. Or if you do a squat same thing: you will have to lift your 100 pounds weight up and down.
Another good exercise to do a home is called the dip. Take a chair, put it against a wall
Sit down. Slide off the chair and bend your arms and lower your body towards the floor. Go up and down and you will work out your biceps with these dips.