you take protein supplements if you exercise...or eat more
basically, it's a simple thing of upping your protein intake if you are active...it's just a wise health thing...you don't have to
example: if you are a desk jockey and don't do anything else...you only need the "standard" 60grams of protein a day
also, there is a difference in what type of exercise you are doing...
if you only exercise...or exercise to stay fit, maintain...you won't gain weight, even if you consume extra protein...if you eat too much protein but don't use it, the energy converts to fat, extra calories...if you consumer a lot of protein but do exercise that burns calories rather than build muscle...it evens out
right now I would say I am maintaining...so I don't consume inordinate amounts of protein...and I'm a vegan.
it's easy to build, but you have to figure out the right regimen for you and what you want to achieve
backup...I think you are doing too much of "non building" exercise