Underestimate at your own risk.

[River Song]

Taking for example the body builders. They may be extremely fit, but IMHO fit in one direction only. The reason for their extreme fitness, (and you can apply this across the categories mentioned in the OP) - the reason that they are superb in their chosen skill-set is that they are TOTALLY focussed - i.e. it's an all consuming passion.

But they are likely to be useless in some other areas. Thats why although my fitness is not good, I'm pretty useful in lots of other areas. A bit of a generalist but i reckon I've got a good chance of surviving.