(1) Don’t think laptops are a good idea for me : I am more of a pen (rather pencil – see (2)) and paper person, who likes to write out ideas on paper first. I tend to code only when I am pretty sure of the structure of my code. I don't use my editors as my scratchpad (python/ruby are changing that a little now... Ah! I almost sense you asking whether I was living under a rock until now? Unfortunately, yes - under one called Java). And when you know what you are going to write it usually doesn't take a lot of time -for which I can arrange for being in front of my desktop.
(2) Pencils: Use pencils to take notes, write exams with pencils. Maybe I like the sound graphite makes when it moves on paper. Or the feel of it. Maybe since I hold my writing instruments vertically pens tend to run out of ink temporarily; or tear paper when I try to write fast. Maybe I hate the many scratches I would have to make with a pen when working on a rough idea - erasing out parts to replace them with better ones is so much more convenient. Maybe I hate turning pages (because the scratches are now an ugly collective clutter) when working on an idea - it affects my flow.
(3) Math: Like math. Maybe the world is not such a deterministic place as it is when I am staring at a math problem in the small universe of a notebook page in front of me. I like the way it challenges me. Maybe I like the way it makes me feel about the world : despite its superficial lack of structure problems can be broken into predictable smaller sub-problems.
(4) Rains: I just get lost when it rains.
