Hello ThriftyCook, that is a very common challenge when cooking boneless, skinless chicken breast. Because it is an extremely lean cut of meat with almost no intramuscular fat, it dries out rapidly if exposed to high heat for even a few minutes too long. Traditional home cooking methods actually rely on a few simple, natural techniques rather than any artificial marinades.
First, make sure the meat is an even thickness. Chicken breasts naturally taper from thick to thin, which causes the thin end to overcook and turn leathery before the thick end is fully safe to eat. You can gently pound the thicker section with a rolling pin or the bottom of a heavy skillet between sheets of parchment paper until the whole piece is uniform in thickness.
Second, use a simple salt brine. Our grandmothers often used basic salt water or dry brining. Dissolving two tablespoons of regular table salt in four cups of cold water and letting the chicken submerge for 20 to 30 minutes will help the protein fibers retain moisture during cooking. If you are short on time, simply seasoning the meat generously with salt 30 minutes before cooking and leaving it on the counter will achieve a similar tenderizing effect.
Third, monitor the internal temperature carefully. Chicken breast is fully safe at 165 degrees Fahrenheit, but if you remove it from the heat when the thickest part reaches 160 degrees, carryover heat will finish the cooking as it rests without boiling away all the natural juices.
Finally, always let the meat rest on a cutting board or warm plate for about five minutes before slicing. This allows the internal juices to redistribute throughout the muscle fibers rather than spilling out onto your board.
I hope this helps you get tender, juicy results with your sale chicken.