Keep your head up! I have battled a long war with depression and I know what it feels like to be sad.... I even had an attempt at suicide at one point but looking back... I would never do such a thing now. The best piece of advice I can give you is this; any problems you have now are all...
Depends What I am doing ATM, Sometimes I just surf the web and lose track of time... then end up being on the computer for 5-6 hours... But on a daily basis... usually 2-3 hours. I can't spend too much time on the computer or else I get bad vertigo :D