http://www.washingtonpost.com/blogs/answer-sheet/post/the-hardest-jobs-to-fill-think-plumbers/2012/07/07/gJQA4wW3UW_blog.html
In the event that I tire of working in education (unlikely), I think I might consider being an electrician. Not quite as messy as a plumber or strenuous as a bricklayer and still a well-paying, honorable skilled trade.