if meds aren’t an option you’ll need to work on CBT stuff or developing coping strategies with a psychologist (things like chopping the task into little bits, getting a list set up that you can tick off, doing 30 mins of that, then 30 of something else, setting timers, etc). it’s worth working on those meds or not- cos pills don’t exactly change habits. 
bguntoor, have you tried strattera, effexor, or wellbutrin? different kinds of meds.
having a ‘coach’ (aka: annoyed boyfriend) trained to start asking me at a certain point: ” ok, so bedtime in an hour, so what have you got left to do? have you done that catlitter yet?- you got 20 mins! lets get those jammies on babes! ok, bedtime was 10 minutes ago, come on, why aren’t you in bed yet? you need to go to bed madam- remember how tired you’ll be tomorrow! hup hup hup! get on with it! stop stalling! right. now: BED! bed. beeeeed. bed bed bed.” until i give up and go to bed has helped pretty well for me- it keeps me on track, provided i don’t yell at him to ‘eff- off cos i know what i’m doing’ so much that he refuses to ‘encourage’ me further. fine line, fine line. 
we’re hoping to get to a point where he just gives me a look and i say ‘yeah, alright, i’m going’, and he doesn’t even get yelled at once- poor boy.
if you’re a bit more aimiable and less hostile than me that sorta thing might help, otherwise you can pay someone to do the same thing on a slightly different level- they’re called a ‘life coach’.