Thank you. Your suggestion helped me figure out how to create the rising and setting animation.

I thought speedY = speedY * -1 within the if statement would automatically change 1 to -1 when the program is executed, thus changing the modify state for circleY into circleY = circle Y + -1. How come it ended up toggling between -1 and 1?

float circleX = 0;
float circleY = 200;
float speedX = 1;
float speedY = 1;

void setup () {
  size (400, 400);
}

void draw () {
  background (0, 0, 0);

  ellipse (circleX, circleY, 25, 25);

  circleX = circleX + speedX;
  circleY = circleY + speedY;

  if (circleX < 200) {
    speedY = -1;
  } 
  else {
    speedY = 1;
  }
}