First we need to identify and diagnose the knee pain correctly . Take precautions biomechanocal postural correction as per lifestyle and strengthening exercises  targeting specific knee muscles  to be done .

Calf  stretching exercise. Towel roll press exercise. Avoid long standing

You should find out the root cause for your pain. How long do you have this pain?

Until the exact reason of pain is recognised, alternate hot and cold water compression.

First identify the lifestyle and activities that are giving you pain and modify them such that the body doesn't feel irritable. it will be related majorly to sitting habits and environment.

What kind of pain is in lower leg? Because sometimes the pain in leg is because of nerve from back if that so then exercises were different otherwise for knee pain there strengthening exercise for knee joint muscles and patellar mobilisation is required...

We have certain protocols to follow. First a proper Assessment to be done to diagnose what kind of problem or injury. There are many causes for knee pain or calf pain or leg pain. Without doing assessment or special test or diagnosis its not advisable to prescribe Exercise. 2. Leg pain can have causes that aren't due to underlying disease. Examples include heavy physical activity, lack of activity, prolonged standing, injuries, sprains or strains. So according to your life style we need to plan your Exercise workout.

First need to do proper assessment and find out the root cause. Then only we can suggest exercises. There can be different reasons of leg pain and knee pain. Need to know proper history as well.