First, learn to live in denial.
Don't address any feelings directly. Feeling sad? It was just a rough day, you'll feel better tomorrow. Burst into tears? Maybe you're PMSing. Answer friendly questions with either explosive sarcasm, or complete avoidance.
Second, love to sleep.
Fight it at first and stay up until three A.M. But once you're asleep, don't leave the bed for ten to twelve hours. Struggle to get up in the morning (or mid-afternoon). Take two hour naps in the evening. Still feel tired every minute you're awake.
Third, distance yourself from friends and family.
Respond to texts 24-48 hours later. Never return phone calls. Keep your phone on Do Not Disturb so that you are not alerted to their positivity and questions. Make plans and then cancel at the last minute, slowly causing your best friends to become agitated and frustrated. Text your mother back once a day, but make it short and sweet. When she asks to call, say you're about to get in the shower. Doing homework. Don't answer.
Feign forgetfulness. No wait, actually forget. Plans, meals, to shower, to pick up toilet paper from the grocery store on your way home. Use paper towels for two days. When you do shower, forget to shave your legs. Some days you don't change out of your pajamas, so what does it matter.
Become lazy. Wash dishes, but leave bits of food on them. Listen to your boyfriend complain about it. He tells you not to worry about doing them anymore. He'll handle everything. Watch while he takes out the trash, walks the dogs, sweeps the floors, unclogs the drain when your hair has accumulated around the grate and the water sits in the tub, leaving two inches of dirty water that cover your toes. It's okay, he says. You have a lot going on. I feel worse. It's not okay.
Don't admit defeat. Pretend to be charge of your emotions. Don't seek help from professionals or friends. Struggle everyday and try to hope it will get better.