Hi Bonnecanyon,
I don't know what kind of decision that you are facing, but I've found a couple of techniques that are lifesavers for me.
The first is: routine. I know that I'm not a fashion plate at work. When I find clothing that fits or feels comfortable, I buy several sets. I lay out a week's clothes in advance simply by placing pants/jeans/slacks in a pile, shirts in a pile, (folded, mind you) and just grabbing the next one in the line in the morning. My lunch is done the same way. I eat pretty much the same thing daily with little variation. This might sound incredibly boring to some, but it's actually really soothing to me.
Housework is done the same way. I break things into routines. FlyLady.com saved my life a few years ago with the mailed reminders of which 'zone' I'm in this week. I'm still not pin-neat, but at least I don't have to bar the door to visitors.
Work has a routine. Come in, boot into the computer, check calendar, check voicemail, check e-mail, do small quick routine things fast, break all other large tasks into time blocks. I don't have to think, you see. Not there, at least.
The second thing is: timers. I can't tell when time passes. At all. Even if the meeting is only 10 minutes away I'll miss it. I need that timer. I have a cell phone that I carry with the timers set. I have a 'task timer' that I picked up in a dollar store.
The third thing is: break it into pieces. This is much harder, but I can do it if I'm fresh, had sleep, no one is around, and I get some silence. I take larger tasks and chart them out into pieces. That's hard to explain in a generic way, but for instance, if I have a report on data due, the parts would be: 1) decide the data types I need 2) pull the data from the database 3) pull it into a spreadsheet 4) set pivot points 5) write a short explanatory write-up. From the steps, I can estimate that the time needed for each step is 1) 15 minutes 2) 10 minutes 3) 2 minutes 4) 15 minutes 5) 1 hour (Yeah, 1 hour. When I'm writing for an audience, I write slow.) So the task takes 1:42, and I round that to 2 hours.
Now, during the planning of how to break things into pieces, I tend to get slightly panicky. Not full blown panic, but occasionally I'll run into something that isn't quite cut-and-dried and I'll have to think. The no people around and quiet are key for that. So the planning takes me hours some mornings. Luckily, I'm allowed some flex time, and my work hours are 6:00 am - 2:30 pm these days. That early morning quiet is a blessing. When I hit a point where I'm starting to get panicky because I can't decide, I get up and walk in circles. I go make tea. I lean back, stare at the wall and pant. (Yeah, I have to constantly work on breathing.) I get back to it in a few minutes, but I let myself calm.
I don't know if that helps. But it may help someone else.