Add the water to a small saucepan and bring to a simmer over medium-high heat.
Pour the hot water into a coffee mug. Add the whiskey, lemon juice, and honey. Stir until the honey has dissolved. Adjust the honey and lemon to taste (it shouldn't be overly sweet).
Garnish with a lemon slice and/or cinnamon stick, if desired. Serve immediately.
Notes
I usually use Irish whiskey for my hot toddy. American whiskey and Scotch whisky will both work as well.
If you have a Keurig, you can use it for the hot water instead. Just be sure to run a hot water cycle first to clear out any coffee residue/taste so it doesn't affect your cocktail.