It's because you think 'time' exists in heaven.
You have the very shallow and childish idea that it's above the clouds with angels and harps.
Heaven (to be in the very presence of God, the one who created you, your heavenly Father) is the most blissful and glorious experience you can have.
There is nothing in this world that compares.
1. Time doesn't exist, time and space was created by God and only applies to this universe. God is outside of time.
2. You get a new resurrected body, incorruptable without sin. Can you imagine a perfect you?
3. You get to see God face to face and not die.
4. You get to travel the cosmos and see everything there is. You get to review all of human history (from beginning to end) and glorify God and His awesome power, holiness, righteousness.
Let me reiterate that time does not exist, you can't get 'bored' in heaven. Negative emotions and feelings don't exist in heaven. It is a perfect paradise and there is always something to do.
Heaven is beyond comprehention. It can't be described with words, it is beyond our capability of understanding. It is a different dimension.
Also, eternity will be spent on the New Earth (restored to Edenic conditions) but my point still applies.