Prep your produce. Wash everything well.
Trim celery ends. If using a regular cucumber with thicker skin, peel it. Peel ginger and lemon if using whole lemon.
For a juicer: Feed cucumber, celery, ginger, lemon, and apple through the juicer.
Stir the juice to combine, then taste and adjust lemon or salt.
For a blender: Chop everything into chunks. Add to blender with 1/2–1 cup cold water and blend until smooth. Start on low, then increase to high for 30–45 seconds.
Strain if you want a smoother texture. Pour the blended mixture through a fine mesh strainer or nut-milk bag.
Press to extract the juice. If you prefer a thicker, smoothie-like drink, skip straining.
Chill and serve. Add ice if you like it extra cold. Taste and add a squeeze more lemon or a pinch of salt if needed.
Garnish (optional). A thin cucumber wheel or celery leaf looks fresh and inviting.