'Flesh' in the Bible

I searched in my heart how to cheer my flesh with wine, my heart yet guiding me with wisdom, and how to lay hold of folly, until I might see what it was good for the sons of men that they should do under heaven all the days of their lives.

Therefore remove sorrow from your heart, and put away evil from your flesh; for youth and the dawn of life are vanity.

Furthermore, my son, be admonished: of making many books there is no end; and much study is a weariness of the flesh.