Toss chicken, flour and garlic in medium bowl; set aside.
Melt margarine in 12-in. nonstick skillet over medium-high heat and cook chicken, stirring occasionally, until chicken is thoroughly cooked, about 6 minutes . Remove chicken from skillet and set aside.
Stir broccoli into same skillet and cook 1 minute. Stir in water and Knorr® Homestyle Stock - Chicken until Stock is melted. Reduce heat to low and simmer 3 minutes. Return chicken to skillet and heat through. Stir in lemon juice.