Way too Thin

I have been experiencing a lot of pain in areas such as my shoulders and knees. These both are very weak with v little muscle after neglecting my health for a number of years, to say the least. I’m now eating right and need to start exersizing right.

I need some advice on what kind of exersizes are best for building stronger knees and shoulders. Last thing I want is to try a lift/exersize that I simply shouldn’t be doing yet.

I am 6’3 and weigh 12 and a half stone, a healthy weight for someone who is 22 and 6’ but I certainly don’t have the muscle/broadness I should have.

Any advice would be greately appreciated.

You might start lifting light weights(that you can do 15 reps with) and focus on learning proper form for a start. Swimmimg is also a good option. Develop the habit of being active.
Maybe 6 days about 20 min than 30, 40.