Slice the chicken breast thinly and season with salt and pepper.
Heat olive oil in a pan and grill the chicken breast on both sides.
Prepare whole wheat bread or sandwich bread.
Spread mustard or low-fat mayonnaise on the bread.
Layer chicken breast, lettuce, tomato, cucumber, and sliced cheese in order on the bread.
Cover with another slice of bread to form a sandwich.
Serve with coffee (such as an Americano) if desired.