I do something small and fun, so that I have the energy to takle something not-so-fun. Then I set up systems so that the job isn't as bad as it otherwise would be - if I'm doing grungy work, such as dealing with mouldy stuff (which I'm allergic to and makes me really sick) then I wear rubber gloves, etc, so that I won't be even more weakened by contacting te energy of it through my hands. (I just wish I had a good mask/filter, or one of those "personal air" filters!)

If I have the energy after doing something fun, and yet as soon as I think about doing the thing I'm putting off, my energy disappears, then there is an emotional or allergic problem with the thing, and I try to either do it at once, or make a concious choice to procrastinate. There is nothing wrong with procrastination. It's actually a survival mechanism. Unfortunately, sometimes the things you need to do are the very things that make you sick.

But if it needs to be done, it really is just a matter of forcing yourself to do it.