Whether you're in the kitchen or the bedroom, it's a lot easier to get creative when you have some time to work with. That's also true in the gym. With the extra 15 minutes from your normal 30-minute workout, you can not only burn more kilojoules, but also fine-tune and amplify your workouts to develop the areas you typically neglect. "With 45 minutes you will have enough time to add that extra little something that can dramatically change the way your body looks and performs," Mejia says.

OPTION 1: include agility

Add agility drills to work on balance, skill, and coordination, which can help prevent injuries and improve sports performance. Ernster suggests running with quick feet through an agility ladder at the end of a workout. Go back and forth as fast as you can and keep your toes on the ground for as little time as possible. Next, side-step through it. If your gym doesn't have a ladder, make your own with sticks or tape, spacing the lines about 30 centimetres apart, or simply go through the motions for the same benefits. To keep your muscles quick, do 10 minutes of agility drills at the end of a 30-minute strength routine. Along with ladders, try grapevines (moving sideways, quickly step out on your right foot, cross your left behind, step right again, then bring left foot back in. Repeat back to the left and so on) and 180-hops (hop and turn 180 degrees, and then turn back, jumping in both directions). Next, spend five minutes stretching and cooling down.

OPTION 2: isolate

Add ancillary exercises to your strength workout, Dr Cummings says. Once you work the large muscle groups, work the smaller ones (like wrists and calves) to polish your shape and prevent injuries. For instance, work your rotator cuffs to help strengthen muscles that will help your tennis-swinging and kid-carrying. Lie on your right side with a light dumbbell in your left hand, elbow tightly at your side. Open your left shoulder slightly and swing your left forearm towards the ceiling, but keep your upper arm tucked to your body to create a short, controlled motion. Do 10 repetitions on each side.

OPTION 3: add cardio bursts

At the end of a weights or cardio workout, do driveway (or gym) sprints to quickly speed your heart rate, Mejia says. The quick bursts will boost your metabolism, and the changes of direction work the small muscles and tendons around your ankles. Do a few sets of jumping jacks to warm up, since they'll help prepare your ankles and knees for the quick stops and starts. Place a marker at the end of your driveway or gym (a shoe, a rock or an obliging neighbour) and sprint out to it, touch it, and sprint back. Repeat for five to 10 one-minute intervals and see how many passes you can make during each minute, going for more speed each time.