Keep your abs engaged. No matter what you are doing (walking, running, bicep curls etc) keep your ab muscles tight so they are working extra hard while you work out. Think about "sucking it in"
Step2
Use an incline. If you are on a treadmill or elliptical machine, increase the incline level. This will make your body work harder. Varying the incline, such as a hills workout will really optimize your workout.
Step3
Try to add an element to your move so you get a full body workout. Doing squats, add in a bicep curl everytime you go down. Do lateral raises with free weights while lunging. Be creative about ways to double up on your moves to include more body parts
Tips & Warnings
Always consult a doctor or trainer if you are just beginning a workout program and need guidance