A good place to start is to think about exactly why that piece got laid aside indefinitely to start with. That is very important and may be quite different for each UFO you consider. The reason you gave up on it will give the key as to how to get back going on it too.Some examples of reasons are:
1) It became boring or monotonous - a common problem with single colour backgrounds once the main picture/design is stitched in cross stitch or needlepoint pieces. It could be that it's the same technique over and over and is dull when you want more variety, or it could be that the colour(s) don't inspire. Whatever the detailed reason, boredom is the main thing. This was part of the problem with my dog thread painting.
2) You made a mistake with it, had to pull a large amount out and got disheartened. Some pieces you make a good and motivated start on only to have the wind completely knocked out of your sails by seeing all that input wasted. That happened with the hardanger piece you can see here. I miscounted in the centre, ended up having to frog about 75% of the work thus far and got fed up and put it on one side for about 7 months. If you look closely at the photo, you can see the holes where I removed threads!!3) The project has outfaced you as it is either too large, too hard or both. This was the other half of the dog problem. Being overwhelmed by a task can be totally paralysing.
4) You just have no motivation to finish it. You may not even like the design anymore, or it may have been a class piece that you had the impetus to do whilst attending the class, but now don't feel any push to complete. Or it may be just a piece you liked, but that lacks purpose, so you feel no urgency to get on with it and other, more interesting or more appealing projects have pushed it into the UFO basket. This was also relevant to my hardanger piece as, originally, I'd intended it for someone's wedding gift, then I gaffed up and realised that I didn't feel I even liked them enough to go to all that trouble....
5) You simply have far too many things on the go at once and therefore you just can't work actively on them all. You have a dozen or so WIPs and you try to put a stitch or two in on those, but you know that several of those will have become UFOs over the next few months because you will have started a number of new things and they will push current WIPs off the production line.
Sounding familiar at all? Do you see yourself and any of your UFOs in the above scenarios? I'm sure you do. So, how do you get back going again? Well, here are some suggestions to get each category of UFO back to WIP status.
1) A boring UFO can be finished slowly and steadily by working one or two lengths of thread on it before you move on to more pleasant and interesting projects. You can also take a boring project in hand when you're watching TV (it's all tent/cross/basket stitch in one colour, so you don't need to concentrate greatly), or when you have someone to talk to. You're giving the other activity most of your attention, but your hands can be productive without you really missing the show or being too pre-occupied to be good (and polite) company. Another take on this one is to do 10 minutes on it at the start of each stitching session or a certain amount of time per week to it. Whichever works best for you, but make sure that it does work! That's why I suggest working on the boring project at the start of your session as it makes sure that it happens.2) A disheartening project can be approached in much the same way. Take it out and do a little - paying very careful attention to how it went wrong in the first place. Work at it little and often and, who knows, once you get past the problem area, you may well find that you're enjoying it again and you can go full steam ahead.
3) Dealing with an overwhelming project can be more tricky. Generally, if it's too large, then the above mentioned 'little and often' approach will soon see it come down to a more manageable size, both in your mind and in your hands. Feeling that it's too difficult may be another matter. In this case, building confidence is key. You may need to try small sections of the piece and allow your success to build your confidence, or even leave it for the time being and work on smaller projects/samples of a similar type until you have the needed know-how to approach your more major piece with confidence. To be honest, the method I used with the dog was to simply force myself to do it. The most major spurts in progress were done on two holidays when I really only had that piece of stitching with me and plenty of time to do it, so I just pressed on with it and saw it working out fine section by section.
4) A piece that you have no reason to bother working on requires that you find one! I had nothing to finish my hardanger for, until I realised that another friend who I was happy to put in effort for was likely to get engaged within the next few months. That got me going again. So, look at your 'no umph for' UFOs and see what you could finish up for whom. Does someone who would like that piece have an event coming up? A big anniversary? A new home? Whatever else you could make it into a gift for. Another good thing about stitching for events is that it provides a deadline. "The wedding is on 12 June, so I have 6 weeks and so I'd best get right down to it!" A piece you don't really like can easily please someone else too, so this method can also take in those things you've gone off.5) Last up is the uncontrolled project starter. The answer to this is to develop some control! If you know you are liable to get sidetracked by yet another new design, simply stop looking at them! Don't buy new kits, magazines, books etc until you've finished a certain number of things. Tell your family and stitching friends so that you can have someone to answer to and who can remind you, and even get tough with you, when needed. Look through your WIPs and UFOs and take out all those nearing completion. Finish those first and get some accomplishment under your belt. Next up get out those about half done and work on those, then move on to those which are only just started (which will be almost as good as a new start anyway). If you don't blog, start one and show off your finishes. Join in, or even start, a 'Finish What you Start' challenge and get tough with yourself. Use some of the suggestions above to keep you on track and to help in each specific case.
If you follow some, or all, of the above suggestions, you can soon see your home become a UFO-free zone and have the pleasure of being able to use the space they're taking up for something else and give joy to friends and family as they receive beautiful, hand-made gifts from you! 
We can often downplay our work, but to others, it's really something. Let yourself have the opportunity of feeling a sense of accomplishment, not only in having finished things off, cleared the decks and had something to show for it, but also in having identified and met a personal challenge - seeing what prevented you from completing a task and overcoming that problem. And then you can perform your happy dance!=)© Elizabeth Braun 2011
