Any person who is always joyful and untouched by any distress is called happy.
As far as Kṛṣṇa's enjoyment is concerned, it is stated that the ornaments which decorated the bodies of Kṛṣṇa and His queens were beyond the dreams of Kuvera, the treasurer of the heavenly kingdom. The constant dancing before the doors of Kṛṣṇa's palaces was not to be imagined even by the demigods in the heavenly kingdom. In the heavenly kingdom, Indra always sees the dancing of the society girls. But even Indra could not imagine how beautiful were the dances being performed at the gates of Kṛṣṇa's palaces. Gaurī means "white woman," and Lord Śiva's wife is called Gaurī. The beautiful women residing within the palaces of Kṛṣṇa were so much whiter than Gaurī that they were compared to the moonshine, and they were constantly visible to Kṛṣṇa. Therefore, no one can be enjoying more than Kṛṣṇa. The conception of enjoyment is beautiful women, ornaments and riches. And all of these were fabulously present in the palaces of Kṛṣṇa, defeating even the imagination of Kuvera, Lord Indra or Lord Śiva.
Not even a slight distress can touch Kṛṣṇa. Once some of the gopīs went to the place where the brāhmaṇas were performing sacrifices and said, "Dear wives of the brāhmaṇas, you must know that not even a slight smell of distress can touch Kṛṣṇa. He knows no loss, He knows no defamation, He has no fear, He has no anxiety, and He does not know calamity. He is simply encircled by the dancers of Vraja and is enjoying their company in the rāsa dance."