Juice the lemons until you have one cup of fresh lemon juice.

In a medium saucepan, combine lemon juice, sugar, and water.

Place the saucepan over medium heat and stir until the sugar dissolves (about 5 minutes).

Optional: Add the lemon zest for extra flavor.

Bring the mixture to a gentle simmer for about 5 minutes.

Remove from heat and let syrup cool to room temperature.

Strain the syrup through a fine-mesh sieve into a clean glass jar or bottle.

Seal the jar and store in the refrigerator for up to 2 weeks.