Help adding start stop push button to program

//I am trying to write an if() statement around my code that allows a push button to initiate the program. Any advice would be wonderful. Thank you!

#include<dht.h> // Including library for dht
#include<LiquidCrystal.h>
LiquidCrystal lcd(7, 6, 5, 4, 3, 2);

#define dht_dpin 12
dht DHT;

#define pwm 9

byte degree[8] =
{
0b00000,
0b00000,
0b00000,
0b00000,
0b00000,
0b00000,
0b00011,
0b00011
};

void setup()
{
pinMode(ledPin, OUTPUT);
lcd.begin(16, 2);
lcd.createChar(1, degree);
lcd.clear();
lcd.print(" Fan Speed “);
lcd.setCursor(0,1);
lcd.print(” Controlling ");
delay(2000);
analogWrite(pwm, 255);
lcd.clear();
lcd.print("Robotics Final ");
delay(2000);
}

void loop()
{

DHT.read11(dht_dpin);
int temp=DHT.temperature;
lcd.setCursor(0,0);
lcd.print(“Temperature:”);
lcd.print(temp); // Printing temperature on LCD
lcd.write(1);
lcd.print(“C”);
lcd.setCursor(0,1);
if(temp >19)
{
analogWrite(9,0);
lcd.print("Fan Speed: 100% ");
delay(100);
}
else if(temp<=19)
{
analogWrite(pwm, 255);
lcd.print("Fan Off ");
delay(100);
}
delay(3000);
}

alexpav37: //I am trying to write an if() statement around my code that allows a push button to initiate the program. Any advice would be wonderful.

That seems at odds with your title.

If you just want the program to do nothing at the start until you press a button you can achieve that with this code in setup()

while (digitalRead(buttonPin) == HIGH) { // assumes it will be LOW when pressed
}

...R