Allah (swt) did not say (In Heaven), neither said (In bliss), rather He said:

فَفِي رَحْمَةِ اللّهِ هُمْ فِيهَا خَالِدُونَ {they will be] within the mercy of Allah. They will abide therein eternally}: The Prophet (saws) explained it and said:

“There is none whose deeds alone would entitle him to get into Paradise. It was said to him: And, Allah’s Messenger, not even you? Thereupon he said: Not even I, but that my Lord wraps me in Mercy.”[1]

So we enter heaven by the mercy of our Lord or by our deeds? Answer: By the mercy of our Lord, but by our deeds; Because Allah (swt) said:

وَأَن لَّيْسَ لِلْإِنسَانِ إِلَّا مَا سَعَى (39) وَأَنَّ سَعْيَهُ سَوْفَ يُرَى (40) ثُمَّ يُجْزَاهُ الْجَزَاء الْأَوْفَى (41)

{(39) And that there is not for man except that [good] for which he strives. (40) And that his effort is going to be seen –(41) Then he will be recompensed for it with the fullest recompense}. (An-Najm: 39-41)

You are rewarded for the work, but what made the reward for the work is the Paradise entering? It is Allah (swt)’s mercy, so you will enter heaven by Allah (swt)’s mercy because He made it as a reward for your work.

[1] Musnad Ahmad Ibn Hanbal: Musnad Abo Horayra, Hadith No.7473.