I am 60 years old male individual. I still do athletic activities like running more than 15 km five times a week. I participate in Half Marathon once a year. As a result, may be due to this strenuous workouts, my knees ache but I continue doing my work outs. What is the best way to get relief from this knee pain. I want to continue with my obsession to keep myself fit, please suggest how do I get a trouble free work out at my age.