Waking up and getting out of bed to go to the gym can feel like a living nightmare. If you have the desire to get a better body, but lack energy to get up, you can still get a good at-home workout — without leaving your mattress. By using two essentials — your bed and your body — even the laziest people can achieve their fitness goals from their bedroom.

The bed can be an effective platform to perform both cardio and strength exercises, even for those who are bound by illnesses.

"For those who are chronically ill, a mattress can be your new best friend when it comes to exercising," said Rachel Straub, exercise physiologist, nutrition scientist, and co-author of Weight Training Without Injury: Over 350 Step-by-Step Pictures Including What Not To Do!

Straub believes you can easily work your entire body, in bed, using a mattress and your body. However, she does caution to watch out for improper movement to avoid injury. "Your low back is the primary area of concern when exercising in bed," she said.

Let your body guide you, and don't push yourself beyond your limits. So go ahead, stay in bed, and practice these 6 exercises that will strengthen your core, your back, your glutes, and thighs.

*Floor has been changed to bed in several workouts for the article.

Reverse Crunches

This exercise targets your lower abs and thighs. To do a reverse crunch correctly, lie on your mattress with your knees bent and feet planted hip-distance apart. Place your hands behind your head or alongside your hips on the bed. Gently draw your belly button in toward your spine as you press your back down toward the bed and lift your knees into your chest to raise your tailbone off the bed. Lower your legs back toward the bed. Let them rest between repetitions to make the move easier.

Exercise courtesy of LIVESTRONG.

Side Plank With A Twist

This move will target your abs, obliques, and triceps. First lie down on your right side with you elbow under your shoulder. Your hips should be stacked. Now lift up through the hip so you will have 1 straight line from your head down to your heel.

Stretch your left arm up above your shoulder reaching your fingers towards the ceiling. Bring your left arm down under your body twisting your upper body as you reach behind. Hold the twist for 1 count, then rotate back to start. Lift and twist again for 6 to 10 reps.

Then, come down and do the same thing on the left side.

Exercise courtesy of Fitness Magazine.

Dolphin Plank

Start in Dolphin Pose, knees bent. Then walk your feet back until your shoulders are directly over the elbows and your torso is parallel to the bed. Press your inner forearms and elbows firmly against the bed. Firm your shoulder blades against your back and spread them away from the spine. Similarly spread your collarbones away from the sternum.

Press your front thighs toward the ceiling, but resist your tailbone toward the bed as you lengthen it toward the heels. Lift the base of your skull away from the back of the neck and look straight down at the bed, keeping the throat and eyes soft.

Stay anywhere from 30 seconds to a minute. Then, release your knees to the bed with an exhale.

Exercise courtesy of Yoga Journal.

Bridge

This pose targets glutes, thighs, and core. You're going to start by lying on your back with your feet hip-width distance apart. From there, relax your glutes and allow the lifting up to come from your tailbone. So as the tailbone starts to lift up towards the sky, keep the arms in place.

Take the shoulders back and down as the hips come up. From there you can reach your fingertips underneath, you interlace the palms, press the pinky side into the bed and you stay here. Your heels are pressing down and even back towards your hands to allow the hips to lift up and you just breathe: inhale, exhale. To release, release the hands first, press your hands down, and then you can slowly start to roll down onto the back. To rest, knees can knock in together, one hand to belly, one hand to heart. Here we go, that’s the bridge pose.

Exercise courtesy of HowCast.

Toe Taps

Lie on your back with your legs up and bent at 90 degrees — thighs straight up and calves parallel to the bed. Rest your hands at your sides, palms down. Keep your abs contracted and press your lower back toward the bed.

Inhale and lower your left leg for a count of 2 ("down, down"), moving only from your hip and dipping your toes toward the bed (without letting them actually touch it). Exhale and raise your leg back to the starting position for a count of 2 ("up, up"). Repeat with your right leg and continue alternating until you've done 12 reps with each leg.

Exercise courtesy of Prevention.

Scissor Legs

This move will focus on your lower abs and legs. First, lie on your back onto the bed. Place your knees in such a way that they are bent and your arms resting at your sides. Make sure that you lower your back onto the bed and pull your navel inwards as close as possible to the spine. Drag your knees close to the chest before you release your legs above the hips.

Your legs should be lowered as much as you can to the bed while keeping your back flat. Now stop for a while when you notice your back rises away from the bed. Now begin to carefully spread out the legs wider so that they are more than hip-width distance. Do this without releasing your abs.

Start oblique exercises by swaying both legs back in and crossing your midline. You must allow your right leg to cross over the left leg. Spread your legs wider than hip width, but cautiously and do not release the abs. Start the exercise by swinging the legs back in and past your waist. Let your right leg cross on top of your left leg. Then let the left leg cross onto the top of your right leg. Do this 12-15 times.

Exercise courtesy of Stylecraze Fitness.