Im 18 Years old and my knees are starting to feel a little weak. What can i do to make them stronger?

Im 18 Years old and my knees are starting to feel a little weak. What can i do to make them stronger?
Excercise.
Depending on you weight, you can take health supplements. Visit a GNC store and talk to the rep. for recommandation.
Good Luck !
Drink more milk and take fish oil.
start walking more as when you walk more your legs will get stronger. you must not do alot. the more you walk the stronger they will be.
Incorporate more proteine in your diet(and take a multi vitamin) and do LIGHT strength training around the knees ( ie leg press) Also eat a lot of things with olive oil. It helps maintain joint health. If you go running, dont go on pavement, use a treadmill or do low impact workouts such as biking or an elliptical trainer. If you must run outside run on even pavement. If you are heavy, weight loss will dramatically improve knee strength.