Thesis Ponderings

How do you write a conclusion to three and half years of work, where do you begin? I started work on my concluding chapter today (although this isn't the last one that needs writing - still the introduction to do) and sat for some time debating where to start, what I should include, and how to set it out. I decided at the time is was easier just to start writing and worry about the exact details later, as it turned out I think that was the better way of doing it. You can often get so caught up in the little details that the big picture goes out of the window.