The key to happiness:

If you want to be in the company of Allah, the All-Subtle, adhere to His Shariah, show gratitude for His favors, reflect upon His universe
and creation, enjoy His remembrance and listen to His words, and be pleased with Him as your Lord, with His Book as a way, and with Muhammad as a Messenger.

Indeed, a person can only win the company of Allah through endeavor and hard work. And if he gets it, his heart will be filled with cheerfulness and his distress will go away, and he will forget the troubles and hardships of this world