make a flag
int trigger = 0
if (trigger == 0)
{
if (valS == HIGH) { // waits for switch to be pressed, and then:
trigger = 1;
etc
}
or...
while(digitalRead(inputpin) == LOW){}
He already told you the answer.
An example using your code:
int trigger = 0; //globally define the trigger
void loop()
{
valF = analogRead(forcePin); // read value of force sensor
valS = digitalRead(switchPin); // read value of switch
if (valF>=thresHold && trigger == 0) { // waits for force sensor to equal or pass pressure threshold
//and makes sure the button hasn't been pressed before
trigger = 1; //signal that button has been pressed before to prevent re-triggering
delay(1000);
digitalWrite(RedPin, LOW); // turns on red LED
delay(1000); // waits one seconds
digitalWrite(RedPin, HIGH); // turns on red LED
delay(500); // waits half second
}
explain
run once and quit does not have much to do with loop, and I am not sure whats happening
do you want it to push button once, then loop twice and not again or what
(confused, but not trying to alienate you)
I still don't know exactly how you want to do this, but I have an idea.
int valFenabled = 1;
int valSenabled = 0;
void loop()
{
valF = analogRead(forcePin); // read value of force sensor
valS = digitalRead(switchPin); // read value of switch
if (valF>=thresHold && valFenabled) { // waits for force sensor to equal or pass pressure threshold
//and makes sure the button hasn't been pressed before
valFenabled = 0; //signal that button has been pressed before to prevent re-triggering
delay(1000);
digitalWrite(RedPin, LOW); // turns on red LED
delay(1000); // waits one seconds
digitalWrite(RedPin, HIGH); // turns on red LED
delay(500); // waits half second
valSenabled = 1;
}
if (valS>=thresHold && valSenabled) { // waits for force sensor to equal or pass pressure threshold
//and makes sure the button hasn't been pressed before
valSenabled = 0; //signal that button has been pressed before to prevent re-triggering
delay(1000);
digitalWrite(RedPin, LOW); // turns on red LED
delay(1000); // waits one seconds
digitalWrite(RedPin, HIGH); // turns on red LED
delay(500); // waits half second
valFenabled = 1;
}
Each button will enable the other after doing whatever... Did you write the other code or look at it from examples?
I think the original poster has taken his ball home in a huff. 
Hmm, he actually disappeared...
Nothing wrong at all with asking for help, but at least make an attempt to learn what is going on and try a solution yourself.