I agree, Robin. Sin is any transgression of, or want of conformity unto, the law of God. In my opinion, cutting a piece of wood too long and having to cut again is not against any command of Scripture, unless it is due to half-hearted labor.

I would say that many thorns and thistles are a result of the fall in general, but others are due to our own sin.

True godliness is a sincere feeling which loves God as Father as much as it fears and reverences Him as Lord, embraces His righteousness, and dreads offending Him worse than death~ Calvin