The setup() function is just called once, at the beginning of the program.

processing is running setup() only once and then goes to draw() and runs this again and again.

Thus, your Code in setup

1.   if (conditionMet) {
2.     println("working");
3.     myObject = new myObject(20);
4.   }

is never run.

Also you need a var that tells you when an object has been added last time and stores this moment as millis.
In my Code this var has the pretty bad name "timer1".
Then you can check if enough time (I have 800 ms) has gone by.

Try:

1. boolean conditionMet = false;
2. int timer1;
3. void setup() {
4.   myObject = new myObject(10);
5.   timer1=millis();
6. }
7. void draw() {
8.   myObject.draw();
9.   myObject.move();
10.   if (millis() - 800 >= timer1) {
11.     conditionMet = true;
12.   }
13.   //
14.   if (conditionMet) {
15.     println("working");
16.     myObject = new myObject(20);
17.     timer1=millis();
18.     conditionMet = false;
19.   }
20. }

This can be shorten to:

1. final int waitHowLong = 800;
2. int lastTime;
3. void setup() {
4.   myObject = new myObject(10);
5.   lastTime=millis();
6. }
7. void draw() {
8.   myObject.draw();
9.   myObject.move();
10.   if (millis() - waitHowLong >= lastTime) {
11.     println("working");
12.     myObject = new myObject(20);
13.     lastTime=millis();
14.   }
15. }

Thanks for the replies, before I edit anything:

You have to make sure that whatever conditional (if) statement you're using to initialise a new object is only true for one call to draw().  If you look at the code chrisir posted:
1) the condition millis() - waitHowLong >= lastTime is untrue at until waitHowLong milliseconds have passed
2) as soon as the condition is true a new object is created and lastTime is updated .
3) on the next call to draw the condition is false again and stays that way until another waitHowLong milliseconds have elapsed.

In this case myObject is replaced so you'll only ever get one thing drawn regardless of how many times you create it.  If you were using an ArrayList then you'd get one new copy of MyObject() periodically .  The code's confusing because myObject = myObject(20) will break - don't give the name of an instance of a class the same name as the class itself.  If you want something to only happen once then add a global boolean that tracks whether you've done that thing or not and check that boolean's state in the conditional as well.

Okay, I should have made my original question clear :)

1st

See https://forum.processing.org/topic/displaying-new-screen#25080000001340109

Ah yes, I'm using states in my game already, for my different menu screens (options, controls etc).

Okay, I'm still in this situation:

It's Not a question of Time (or shouldn't be)

Or count how many you have and stop when you have enough

Look again at the Post  http://forum.processing.org/topic/how-can-i-initialise-an-object-from-an-arraylist-when-the-program-has-been-running-for-x-amount-of-time#25080000001523039