bool someGlobalVar = false;

void setup() {
  Serial.begin(9600);
}

void loop() {
  Serial.println("loop");
  Serial.print("someGlobalVar: "); Serial.println(someGlobalVar);

  if (someGlobalVar == false) {
    Serial.println("switching...");
    someGlobalVar = true;
  } else {
    Serial.println("not switching...");
  }

  delay(1000);
}