I frequently have projects both personal and professional that for whatever reason develop large gaps between periods of creative work. These gaps are perhaps the biggest contributors to creative-misfires and degradations in my personal productivity. When starting and engaging a projects I enter the ZONE and my focus is channeled on the actions ahead. Unfortunately most of my projects take many more hours that I can possibly commit to in one sitting and upon return my focus must be reacquired. Over at LifeDev there's a great post about this phenomenon and the frustrations of "mental bookmarking" your last position in a project, reacquiring your state of mind and resuming the project with the same diligence, determination and vision.

I’ve found that the only way to really wrap my head around something is to force myself back into the “zone”, so to speak. If it’s writing, I’ll re-read everything I’ve written, so as to recapture that mindset. If it’s programming, then I’ll have to go look at SVN commits, or just start digging around the code. Anything to get my mind back into the frame of the task at hand.

Once I finally wrap my head around the project, it’s not hard to get back into gear. It’s the process of climbing back up to the previous ledge and pushing forward that is a tad difficult.
There are plenty of techniques to help you remember where you left off in a project. Here are a couple that I use that never fail me:

• If I know I’m going to be revisiting the project quickly, I leave open all tools, documents, etc., so it’s like a visual snapshot
• I take detailed notes as to what I was thinking, feeling and doing when I stopped working

In my workflow I am now keeping a log of my last thoughts on a project's actions and making note of open loops. So far I am discovering it's much easier to resume the project, appraise how much time remains and take bite sized actions towards the final product. Bonus points for the added ability to resurrect the creative thought process from when I had broken my attention from the project.

Take a look at LifeDev for the entire article and some of the great ideas in the comments.