Simple Arduino Hulda Clark ZAPPER with Timer function

//Arduino ZAPPER

#include <Arduino.h>
#include <U8g2lib.h>

//U8G2_ST7565_NHD_C12864_1_4W_SW_SPI u8g2(U8G2_R0, 10, 9, 12, 11, U8X8_PIN_NONE);
//U8G2_SSD1306_128X64_NONAME_2_SW_I2C u8g2 (U8G2_R0, A5, A4);
U8G2_ST7920_128X64_1_SW_SPI u8g2(U8G2_R0, /* clock=*/ 13, /* data=*/ 11, /* CS=*/ 10, /* reset=*/ 8);
byte inPin1 = 5; // digital input sw-1
byte outPin1 = 7; // digital output sw-3
byte time_healing = 7; //time healingenia (30kHz generation)
char time_healing_str[3];
byte time_healing1;
byte time_pause = 20; // break time until next healing in min.
byte time_pause1;
char time_pause_str[3];
byte cycle = 4;
char cycle_str[3];
byte interruptPin = 2;
byte ZapperPin = 4;
char* message;

void setup() {
   u8g2.begin();
   pinMode(inPin1, INPUT_PULLUP); //setting the pin as a digital input
   pinMode(outPin1, OUTPUT); //output to the squeak
   pinMode(13, OUTPUT);
   digitalWrite (13, LOW); //turn on LCD backlight
   pinMode(8, OUTPUT);
   digitalWrite (8, LOW); // giving mass to power the LCD
   pinMode(ZapperPin, OUTPUT); //declaration of Zapper output port
   digitalWrite (ZapperPin, LOW);
   Serial.begin(9600);
}

void loop() {
   //waiting for Start
   cycle = 0;
   digitalWrite(inPin1, HIGH);
   do {
     message = "  PRESS START";
     DisplayLCD();
   } while (digitalRead(inPin1) == HIGH);
   //Getting started
   cycle = 3; beep(); Work();
   beep(); Pause();
   cycle = 2; beep(); Work();
   beep(); Pause();
   cycle = 1; beep(); Work();
   beep(); delay(50); beep(); delay(50); beep();
   time_healing1 = 0; time_pause1 = 0;
}

void Work() {
   time_healing1 = time_healing + 1;
   message = "HEALING";
   for (byte j = 1; j <= time_healing; j++) {
     time_healing1--;
     strcpy(time_healing_str, u8x8_u8toa(time_healing1, 2)); // convert healing1 to a string with 2 digits
     DisplayLCD();
     Generate_30kHz();
   }
   time_healing1 = 0;
}

void Pause() { // generate pause
   time_pause1 = time_pause + 1;
   message = "PAUSE";
   byte s, m, th;
   for (th = 0; th < time_pause; th++) {
     time_pause1--;
     strcpy(time_pause_str, u8x8_u8toa(time_pause1, 2)); // convert pause to string with 2 digits
     DisplayLCD();
     for (s = 0; s < 60; s++) {
       delay (1000);
     }
   }
   time_pause1 = 0;
}

void Generate_30kHz() {
   for (byte z = 1; z < 60; z++ ) {
     for (int i = 1; i < 30000; i++) {
       for (byte j = 1; j < 67; j++) {
         PORTD = B00010000;
       }

       for (byte j = 1; j<66; j++) {
         PORTD = B00000000;
       }
     }
   }
}

void beep() {
   digitalWrite(outPin1, HIGH);
   delay(100);
   digitalWrite(outPin1, LOW);
}

void DisplayLCD(){
   strcpy(cycle_str, u8x8_u8toa(cycle, 1)); // convert cycle to string with 1 digit
   u8g2.setFont(u8g2_font_6x12_tr);
   u8g2.firstPage();
   do {
     u8g2.drawBox(0, 0, 128, 10); // draw a black background
     u8g2.setDrawColor(2); // select the writing mode
     u8g2.setFontMode(1); // white on black
     u8g2.drawFrame(0,11,128,53);
     u8g2.drawRFrame(2,13,124,49,10);
     u8g2.drawStr(40, 8, " ZAPPER");
     u8g2.setDrawColor(1); //return to writing mode
     u8g2.setFontMode(1); //black on white
     if (cycle == 0) {u8g2.drawStr(20, 40, message);}
     if (cycle > 0) {
     //if (time_healing1 > 0 or time_pause1 > 0) {
       u8g2.setFont(u8g2_font_6x12_tr);
       u8g2.drawStr(15, 50, message);
       u8g2.drawStr(95, 50, "min.");
       u8g2.setFont(u8g2_font_9x18_tn);
       if (time_pause1 > 0 ) { u8g2.drawStr(70, 50, time_pause_str);}
       if (time_healing1 > 0 ) {u8g2.drawStr(70, 50, time_healing_str);}
       u8g2.drawStr(55, 30, cycle_str);
     }
   } while ( u8g2.nextPage() );
}