Place the chicken breasts in a single layer in the bottom of a large saucepan. Season with salt and pepper. Top with lemon slices and fresh thyme and rosemary sprigs.
Fill the saucepan with cold water until it reaches 1 to 1 ½ inches above the chicken breasts. Stir in the soy sauce.
Bring the water to a boil, then cover the saucepan and reduce the heat to low.
Lightly simmer until the chicken breasts are just cooked through, about 15 minutes. The cooking time will vary depending on the thickness of the chicken breasts.
Remove the chicken from the saucepan and let the chicken cool. Slice or shred the chicken. Serve right away or refrigerate, covered, for 2 to 3 days.