Place the chicken breasts in the bottom of a large pot, then season them lightly with salt and pepper. The amounts in the recipe are just a suggestion, so don't feel pressured to measure. Give each breast a nice sprinkle. If you are cooking a lot of chicken breasts, you can overlap them slightly. If you have a lot of overlap, use a larger pot.
Cover the chicken with 1 inch of water.
Place the pot on the stove and bring the water to a boil. Once the liquid is boiling, reduce the heat and let simmer until the chicken reaches an internal temperature of 165 degrees F on an instant-read thermometer or is no longer pink in the center, about 8 to 16 minutes, depending upon the size and number of chicken breasts that you are poaching. A 10-ounce chicken breast will need to simmer for about 12 to 14 minutes. Remove the chicken from water and let rest until cool enough to handle. Dice, slice, or shred as desired.
Notes
This method for how to poach chicken is intended for boneless, skinless chicken breasts. It also works well for boneless, skinless chicken thighs or bone-in chicken breasts too, though you will need to adjust the cooking time accordingly. If using bone-in chicken breasts, extend the cook time; for thighs, check them early.
Store leftover chicken in an airtight container in the refrigerator for up to 4 days. If dicing the chicken, I prefer to cut the chicken just before serving. If shredding, I find that the chicken is the easiest to shred apart while it is still slightly warm, before I place it in the refrigerator. You can shred by hand or use a hand mixer on low speed.