"I'd rather not guarantee myself an enemy without knowing more about the circumstances, so I'll have to pass on that one. The compulsion could work."

"The nice thing about defeat is that once it happens it's over and you don't have to deal with it, whereas many compulsions continue to be relevant indefinitely." 

"Granted, but this enemy doesn't just defeat me, they kill me. How can I possibly arrange a guarantee that I will end up only partly and not completely dead?"

"Well, partly dead is a lot easier than completely dead, if you don't swap out pixie."

"That is not a guarantee, it is a likelihood!"

"I mean, fair, but it also isn't guaranteed that nobody will try to kill you if you don't take defeat. What kind of compulsion were you thinking of? The more often it comes up, the more power it'll give you."

"Does it have to be triggered rather than time-based? Is there an approximate range of things it's possible to specify? Is it possible to deliberately arrange my life to manage when and how often I encounter the trigger, and does my intention to do that matter when calculating how often it'll come up?"

"It has to be triggered, but it can be triggered by something in your mind, such as a sense of time, instead of by something external. It has to be an actual action you could theoretically take, you can't take a compulsion to, being a Jovian moon, crash into another Jovian moon. Yes and no respectively; things that are more common in general require more arranging to manage." 

"The direction I'm thinking along is that it would be convenient to find something that happens naturally a reasonable fraction of the time but isn't that hard to avoid when it's a bad time to be compelled to do something. Actually, though, that's a good question: how is rarity calculated if the trigger is an action I take, like brushing my teeth every day, where I could avoid it but historically haven't and have good reasons not to?"

"That would probably count as a once-a-day kind of thing, for four points. Eight points if you were in the habit of brushing in the mornings, too."

"That sounds lucrative. But I can only do it for things that I am already in the habit of, I can't plan to construct a habit going forward and have that count?"

"You might be able to, if you can precommit reliably enough, but I won't be able to tell for sure without checking, and it's less likely to work if your precommitment is conditional on it working." 

"That tracks... hmm, let me see..."

He thinks about it for a minute, letting go of all other inputs and processes to focus on fitting his mind into the right shape. It should be something that's pretty trivial to do, but easy to distinguish from other activities. It should be something that's not burdensome but also not inherently a bad idea to omit—hence brushing teeth being a bad candidate. It should—actually, he has another question before he proceeds.

"If while I'm forming the habit I fit in an intention to make up for missed occasions on later days, do you expect that to help?"

"It's not likely to be the tipping point between it working and not--unless making up for things helps you form habits, personally--but it might be the tipping point between four points or eight, if it's a twice-a-day kind of thing." 

"Sensible. All right."

He goes back to his state of quiet contemplation. It shouldn't depend terribly much on body plan since he has still not finalized his decision of body plan. It should be something that he won't accidentally do without intending to trigger the effect...

All right. Twice a day, morning and evening, he will spend a minute meditating on his ongoing projects and then tell himself that it's time to pay his dues, with the intent that that then triggers a compulsion to spend the next half hour working on some kind of physical build. If he misses a session he'll plan to make it up within the next week or so; if he has a slow start building the habit, he'll keep track of the approximate number of misses while he's working on it and then spread them out over a longer period of time once he's got it solid.

"Now, how exactly do I test this...?"

"Try reaching for the compulsion," she suggests, "I'll try to guide it as much as I can." 

He makes an attempt to link the compulsion to his newly formed pre-habit.

It wibbles a little, like a top that's about to lose stability, and then it clicks. 

"Oh good!"

"Eeee!" 

Vague impression of excited hand clapping. 

"I'm decently good at intending things, apparently. So, hmm, where were we...?"

"You hadn't commented on how you felt about Crutch." 

"Crutch? Oh, the external implement? Hmm - how hard to come by are these implements? Could it be possible to recreate one myself if I found myself without it somehow?"

"Not very, and yes--you'd have to learn how, but I know of a case where a witch in captivity managed to carve an implement into her own skin." 

"In that case I think I'll take it. Hmm, where does that leave me..."