In one sentence, describe what the following article is about:

Pushups are a classic upper-body strengthening exercise that you can do anywhere. To begin, kneel down on a mat or the floor and bring your knees and feet together. Stretch out on your belly and rest on your palms, with your hands shoulder-width apart and lined up with your shoulders. Rest your toes on the floor and keep your legs together. Tighten your core and keep your back straight as you push up from the floor with your arms until your elbows are straight, then slowly lower yourself back to the floor.  Ideally, you should not let your belly touch the floor before pushing back up again. Try doing 3 sets of 10 reps to start. As you get more comfortable with pushups, you’ll be able to do more in a set. If you’re not comfortable with a full pushup yet, allow your knees and shins to rest on the floor and just push up your upper body. This is a great way to build the upper body strength you need to eventually pull off a full pushup! This fancy-sounding exercise is actually a simple way to work out your upper body, back, and hips. Lie flat on the floor or a mat and stretch your legs out behind you with your toes pointing backwards. Stretch your arms out straight in front of you with your palms facing each other. Exhale and tighten your core, then slowly raise your arm a few inches off the floor while inhaling. Exhale as you slowly lower it down again. Alternate doing this with each of your limbs in succession. Try to keep your back, hips, and head as still as possible while you do this exercise. Planks are a great core-building exercise that work more effectively than push-ups and are easier to do! To execute a basic plank correctly, lie down on the floor or on a mat and place your palms on the floor, shoulder-width apart. Broaden your shoulders as much as possible to engage your back and core. Push straight up through your arms and put your toes under you so that your entire torso and legs are off the floor, keeping your legs and back as straight as possible. Try to hold this position for 20-60 seconds.  Don’t forget to breathe! Inhale steadily in through your nose and out through your mouth while you hold the plank. Lower yourself slowly and gently back to your starting position when you’re done. Frog bridges are a great way to build your butt and strengthen your abs and lower back. Lie down on your back and put the soles of your feet together, letting your knees fall open into a “frog leg” position. Tighten your glutes and abs and slowly raise your hips off the floor until your body forms a straight line from your shoulders to your knees. Then, hold your position for a couple seconds and tighten your glutes before slowly lowering yourself back down to the floor.  Keep doing this exercise as a series of smooth, flowing movements for 30 seconds. Breathe steadily in and out as you go through the whole exercise. Lunges are a good dynamic stretch, but they also help build strength in your lower body and legs. Start by standing with your feet together, then pull your shoulders down and back. Tighten your core and keep your back straight.  Slowly lift one foot and then step forward into a deep lunge with your other leg out behind you and both knees bent. Hit the floor with your heel first when you step forward. Push off with your front leg to return to the starting position.  When you enter the lunge, lower your hips straight down instead of pushing them forward. Try not to sway or lean from one side to the other. Tighten your thighs and butt as you return to the starting position. Heel raises can help strengthen and tone your lower legs. To do a simple standing heel raise, stand in front of a chair or counter. Grab the back of the chair or rest your hands on the counter, then slowly raise onto your toes, keeping your knees and back straight. Then, gently lower yourself back down onto your heels.  Do 2 sets of 10-15 reps. You can also incorporate heel raises into your squats to work out your calves as well as your upper legs! If you feel lost without a coach or personal trainer by your side, workout videos can be a good substitute. Search YouTube for videos that focus on working out out the different muscle groups, or try a strength and flexibility training routine like this one: https://www.nhs.uk/live-well/exercise/strength-and-flex-exercise-plan-how-videos/. You can also use apps with guided strength training routines, such as JEFIT, StrongLifts 5X5, and GAIN Fitness Cross Trainer.

Summary:
Build your arm and shoulder strength with pushups. Strengthen your shoulders and back with contralateral limb raises. Do some planks to build strength in your core. Engage your glutes and core with frog bridges. Work your legs and butt with lunges. Tone your calves with heel raises. Follow along with strength training videos for extra motivation.