Hello! Hope this question is not too stupid!!

I just wrote a very simple code to illustrate a question I have as new aspiring processing coder.  When I am writing code, I always come to the point that I would like to encapsulate the variables (here: float x = 0.0;) that belong to a function or class into its code to have clean logical groups. Unfortunately I cannot do that as they have to be initialized outside the function to work right!?  Is there any way to initialize a variable inside a function just once and not everytime it is triggered by draw() ?



float x = 0.0;  

void setup()
{
}

void draw()
{
println(countUp( 0.5));
}

float countUp( float speed){
    x = x + speed;
    return x;
    }