i wont patronise you but i have a lot of experience of this. its easy to give advice but lots of people are talking sense in their replies. remember, keep pushing, do stuff you dont feel like doing but be REALISTIC - 50% not 100% is the way to start functioning again. most importantly 'give youself a break' all that feeling crap about yourself, its all distorted thinking caused by wonky brain chemistry.
And i always knew physical activity was good therapy but cycling has turned out to be far and away the best form of this i have EVER known,the gym just bored me.
personally i think meds have their place to kick start you out of the worst of it, but i will NEVER take any of that again.....(some of) the professional contact i had years ago was useful but ultimately its you who will regain control and become comfortable in your own skin - hard work but you'll get there,on your own terms and with your own strengths. but always make sure
to get help BEFORE it gets to the stage where its crippling you, wether that be friends, family, professionals or whatever.
Is it seasonal ? just wondered, because i am convinced that SAD is not an illness as such ; i honestly believe that anyone who DOESNT experience a significant lowering of mood through our horrible long, grey british winter must be bloody lucky, i'd emmigrate if i could.
good luck, its worth the fight to beat this horrible thing.