I not really understand why people say something like teaching English in Japan for a year and the like is only something one could do when younger. Also when being older it can be a bonus in your CV (and IS a bonus for yourself). Doing something like this, no matter what age, shows certain qualities.
Of course it gets more difficult when being older...for example if you already have the good paying job you are happy with or a wife/husband and children than its not such a good idea, but in general, if you just have a normal job, no job, a job you are not happy with, no family etc. it is also something for older people.
An example, a teacher from my University went for 6 months to India teaching English there. Well, he hadn´t had to give up his job for this, he was able to take 6 months vacation time and than just started working his job again after returning, but he said, it was one of the most valuable experiences in his life...and the man must be 40+.
I am also not that young and its the second time for me living abroad, one times when I was young and now. And I know both times are/ will be + points in my CV. It may also depend a little what your job is, but if you do something, that is your job (like when you are a teacher already) or very near to your job, why should something like this stop being good just because one is older?
TerokNor