I have a whole lemon, squeezed into hot water in a small cup every morning. Sometimes I add a few flakes of sea salt, which I recently learned to do after a nutrition workshop. The salt aids hydration. Some people have slices, or a squeeze, but being the all-or-nothing girl I am, I go big on the lemon.
For best results, do this on an empty stomach, every morning. It cleanses the liver,
which has been working hard overnight and reboots your immune system.