There are a lot of quotes that people attribute to the Bible that aren't there. One of them is "Cleanliness is next to Godliness." That is not in the Bible.
However, having a clean, healthy body is part of the preparation for serving the Lord. Not only is our strength increased if we are clean and free from germs, but our testimony is also increased. Don't you hate it when the dirty, scary guy is holding up a Scripture sign? It's not a great testimony.
This is a pretty simple concept, but in order to prepare yourself to serve the Lord, take a shower!