Hi i want to do exercise but i can't every time i tried my knees start to shaken i don't know what to do i want to live a good healthy & sexy life.

Start slow: Even if the best you can do is 3 min on a stationary bike or rowing machine, or just walking will get you startd. You can find a great app here called my personl trainer which could help coach you. Also, drink plenty of water and eat a small snack before and after exercise. Good luck.

Weightless exercise: Great to hear that you're going for a better, healthier lifestyle! try exercises that don't require as much weight on the knees, like recumbent biking or spinning. Other lifestyle modifications include choosing a healthy diet with calorie restriction. Best of luck, i hope the best for you!