Here is a workout idea that you can set a timer for 15 minutes and work through. Many of these use dumbbells, but you may use substitutes or no weights at all.

Here are the instructions for the exercises:

Dumbbell Standing Back Fly

1. When performing this exercise, ensure that you maintain a flat or slightly arched back
2. Try to keep your body parallel to the ground
3. Have the dumbbells in each hand
4. Move the weights out and away from each other in an arc motion
5. The arms should be elevated until they are parallel to the floor
6. Slowly lower the weights back down
7. Repeat

Deadlifts

1. Stand upright, holding a dumbbell in each hand, arms hanging at your sides and your palms inward
2. Curl the weight in one hand towards the shoulder in a circular motion.
3. Squeeze the bicep at the end of the lift and slowly lower
4. Alternate hands and repeat. Keep your body still, elbows locked and palms faced inwards throughout the whole exercise. 

Hammer curl

1. Stand up straight with arms hanging and dumbbells in both hands, palms facing in.
2. Curl the weight in your right hand toward your right shoulder, keeping your palm faced inwards at all times.
3. Pause at the top of the lift and then slowly lower.
4. Alternate.

Bicep curl

1. Stand up straight with arms hanging and dumbbells in both hands, palms facing in.
2. Curl dumbbells for both arms at once, twisting your wrists on the way up and keeping your elbows still.
3. Slowly lower and repeat.

Tricep extensions

1. For this exercise, keep your elbows pointing straight up to the ceiling and in line with one another
2. Arms should be parallel and in line with your ear when you extend over top of your head as well as in the downward position.

Squats 

1. Stand with your head facing forward and your chest held up and out.
2. Place your feet shoulder-width apart or slightly wider.
3. Sit back and down like you’re sitting into an imaginary chair. Keep your head facing forward as your upper body bends forward a bit. Rather than allowing your back to round, let your lower back arch slightly as you descend.
4. Lower down so your thighs are as parallel to the floor as possible, with your knees over your ankles. Press your weight back into your heels.
5. Push through your heels to stand up straight and bring yourself back to the starting position.

Plank

1. Start on the floor on your hands and knees. Place your hands under your shoulders. 
2. Step your feet back. For more stability, bring your feet wider than hip-distance apart, and bring them closer together for more of a challenge. 
3. Maintain a straight line from heels through the top of your head, looking down at the floor.
4. Now, tighten your abs, quads, glutes, and hold.