Acting depressed can reinforce your belief that you have no control over depression. Acting depressed can add to your guilt, make you feel even more worthless. It can make it impossible to notice any natural improvement in your mood.
Acting "as if" will not cure your depression, but it will allow you to notice the occasional feelings of almost-good. It can prevent you from adding to the bad feelings.
Don't Stay Inside
Being outside in sunshine or dark, cool breeze, heat or even rain, pulls us outside ourselves. We feel less depressed when we feel connected to the natural world.
Don't Forget Personal Hygiene
Clean up, dress up, spiff up: the mood can only follow...up. Sure, it takes energy to shower, shave, dress, add jewelry and put on a smile, but you'll feel and look so much better!
Don't Sleep The Day Away
Not only will excessive sleep not improve your mood, it will add to your guilt for not being useful. If escape is your goal, find it outdoors or in a hobby.
Don't Leave the Mess
Living in squalor makes you feel guilty and angry with yourself for not being more productive. It reinforces your place in your personal black hole. Pick up the “stuff” you left lying around, clean up the spill on the floor.
Don't Ignore Your Family and Friends
Talking with people who love you, even for just a brief “touch-base” can make you feel connected and pull you out of your isolation. When contact with other people has depleted you, a simple “Hi, I love you,” to someone who cares can be replenishing.
Don't Be A Couch Potato
Vigorous exercise is anathema to depression. It sends blood to circulate invigorating chemicals/hormones and oxygen to your starved brain.
Act as if you were not depressed to keep from sinking through guilt, anger, feelings of worthlessness and hopelessness into a deeper depression.