You need a haircut and don't feel like going out to the salon. Sometimes your hair needs a little trim, or sometimes you feel like chopping it all off. For the very brave (or the very experimental), there is the concept of the home haircut. Cutting your own hair can be challenging, especially cutting the back with a mirror, since every movement you make in a mirror is backwards. It takes a little practice to get the movement down, but once you cut your own hair a few times you'll get used to it and can perfect your technique. If you make a mistake that you can't fix, you can always go to a hair salon and hand yourself over to the authorities.
Before you start, have a mirror in front of you and a mirror on the wall in back of you so you can see the back of your head. Wash, towel dry and comb your hair. Cover shoulders with a towel or sheet. Start by combing your hair straight out from the crown of your head, all around your head like a lampshade. This means it will cover and frame your face, which is where you will start.
Cut around the face first, trim bangs. Make sure bangs reach your eyebrows, since they will shrink later. Cut a small section at a time to desired length, starting at bangs and aiming toward one ear. Always include a bit of hair from the earlier section and cut to that length if you want to stay all one length. When you reach the front of one ear, repeat on other side to front of other ear.
Go back to the first ear and continue trimming behind the ear, taking a section at a time. Trim as far as you can before the angle is too hard to see from the front mirror. When the angle is too hard to see, switch to the other ear, and repeat the same process. When the angle is too hard to see, you're finished with the sides. This will leave you with the smallest possible section to cut in the back, which is the hardest to do.
Face your mirror so you can see the back of your head, and cut the back section to match and connect your two side sections. Cutting in the mirror is tricky, as every motion will be backwards. Take your time!
Pull hair out from in front and behind both ears and look in the front mirror to see if they're even. Trim if necessary. Style as you normally would.