Motion Sensor Stopwatch

#include <LiquidCrystal.h>
#include <Servo.h>

LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
Servo releaseGate;

const int distancePingPin = 9;
const int distanceEchoPin = 10;
const int buttonPin = 6;  
const int servoPin = 7;  
const int detectionDistance = 10;
unsigned long startTime;
unsigned long currentTime;
bool timerStop = false;
int closedAngle = 70;
int openAngle = 170;

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

  releaseGate.attach(servoPin);

  pinMode(buttonPin, INPUT);
  
  lcd.begin(16, 2);
  startTime = 0;
  StartClock();
}

void loop() 
{
  currentTime = millis();
  
  int distance = DistanceToObstacle();

  if (distance <= detectionDistance)
  {
    if (timerStop == false)
    {
    lcd.clear();
    delay(100);
    float currentT = currentTime;
    float startT = startTime;
    if ((currentT - startT) /1000 > 60)
    {
          lcd.print(((currentT - startT) /1000) / 60);
          lcd.print(" Minutes");
    }
    else
    {
          lcd.print((currentT - startT) /1000);
          lcd.print(" Seconds");
    }
    timerStop = true;
    }
  }

  if(digitalRead(buttonPin) == HIGH)
  {
    StartClock();
  }
}

void StartClock()
{
    releaseGate.write(openAngle);
    timerStop = false;
    startTime = millis();
    lcd.clear();
    delay(100);
    lcd.print("Clock Started");
    delay(500); 
    releaseGate.write(closedAngle);
}

float DistanceToObstacle()
{
   delay(100);
   long duration, inches, cm;
   pinMode(distancePingPin, OUTPUT);
   digitalWrite(distancePingPin, LOW);
   delayMicroseconds(2);
   digitalWrite(distancePingPin, HIGH);
   delayMicroseconds(10);
   digitalWrite(distancePingPin, LOW);
   pinMode(distanceEchoPin, INPUT);
   duration = pulseIn(distanceEchoPin, HIGH);
   cm = MicrosecondsToCentimeters(duration);
   return cm;
}

long MicrosecondsToCentimeters(long microseconds) {
   return microseconds / 29 / 2;
}