I never do it anymore, but it worked great until I got a PC, a Psion 5, and especially after my first Macbook. Since then I barely write with a pen, and if I do it's cramped.
This will sound silly and non-sequetor, but bear with me: Get a fountain pen. A $2 Pilot Varsity will get you started.
A fountain pen is a joy to write with. It requires virtually no pressure, especially when compared with cheap ball point pens. The ink flow is regular and heavy, resulting in even crappy writing looking interesting. It makes it fun to write, which makes (me at least) more likely to write whenever I can.
Just be sure to also use heavier paper - the Varsity ink will bleed through the cheap stuff 2-3 pages deep.
The Varsity was definitely my gateway drug into fountain pens. I burned through too many of them in grad school. Fantastic little things. I've since upgraded, but if I'm in a bind I'll grab a few of them at Staples.
I do this too. The lack of interrupts and constraints were also my driver back to blank pages for project planning/outlines/tricky bits to work through. My coworkers do think it's strange that I write so much and then throw it away nearly immediately once whatever I was doing is transferred back to the hivemind.
Pretty much all CS programs have exams where you must write code with pen and paper. It's a bit of a challenge to try and come up with an alternative way of having individual assessment of coding skill (with no help from the Internet or ways to cheat).
Lots of people complain about it but I never had an issue with it. Two reasons why: 1) typically the amount of code is really small and the exercises are very easy anyway 2) I've been writing (pseudo) code on pen and paper since I was a kid (and I still do!) and I find that to be a valuable tool.
Ditto for whiteboard coding in interviews, as long as we're talking about small toy problems, I have no problems doing it on the board.
I swear by wooden pencils and 5x5mm graph paper. I have a nice flipboard with a notepad, a pencil, a sharpener and an eraser attached with velcro.
Measured in straight up typing speed, a keyboard is faster but when you're talking note taking mixed with thinking or something that involved equations or diagrams, I can't get anywhere close with a computer. And there are no distractions on paper.
And why wooden pencils instead of a mechanical one? The smell. The smell of fresh shavings from the pencil sets my brain in the right gear.
I never do it anymore, but it worked great until I got a PC, a Psion 5, and especially after my first Macbook. Since then I barely write with a pen, and if I do it's cramped.