One useful little concept that a friend and I have is that of the antiskill. Like a normal skill, an antiskill gives you both the ability and the affordance to do things that you wouldn't otherwise be able to do. The difference between a skill and an antiskill is that a skill gives you the ability and affordance to do things that are positive on net, while an antiskill gives you the ability and affordance to do things that are negative on net.
For instance, my friend believes that dancing is often an antiskill, because it gives you an affordance to dance rather than have interesting conversations while at parties, and he considers having interesting conversations to be much more valuable than dancing-- therefore, knowing how to dance serves primarily to enable choices that are bad on net.
I disagree with the specific point in this case, but I nevertheless think it's a good example because it illustrates another key principle of skills and antiskills-- whether something is a skill or an antiskill is context-dependent. If dancing will largely prevent you from having interesting conversations, it may well be an antiskill-- but if you go to a lot of nightclubs where loud music makes conversation difficult, knowing how to dance seems very useful indeed!
Another example is the skill of knowing how to fix computers. In many respects this is very useful, and can indeed lead to a profitable career in IT. But-- as I'm sure many of you may have experienced-- having your friends and family know that you know how to fix computers can be very negative on net!
Overall, I find the skill/antiskill framework quite useful when it comes to navigating what sorts of skills, abilities, and knowledge I should acquire. Before choosing my next priority, I often pause to think:
- What affordances will learning this give me?
- In what contexts will those affordances be most relevant?
- Will this be positive or negative on net?
Using this framework has enabled me to discern strengths and weaknesses that I had previously not considered, and in some cases those strengths and weaknesses have proven decisive to my planning.
Eh, I have a black belt and I don't think it's increased my likelihood of getting into fights at all.
Now bodybuilding, on the other hand, is definitely causing an issue via increased testosterone.
I still don't get into fights, though. One useful thing to remember, if one is the sort of person who reads lesswrong, is interested in either of these activities, but doesn't want to get into fights is the fact (I can't remember where I read, this but our purposes, it's instrumentally useful to believe even if false) that the average IQ of individuals ending up in the emergency room because of fight-related injuries is 87 -- not because dumb people are more likely to lose fights, but because smart people are more likely to avoid them. If you think of yourself as "not the kind of person who gets into fights," (because they are mostly idiots) you're less likely to get into fights.