The difficulty of Heaven is that it requires mutual love, mutual harmony, mutuality of purpose. Whereas Hell is potentially a solo venture - we can 'go it alone'. Hell does not need other people, and tends-towards solitude.
It is typical of the value-inversion of an atheist-communist that Sartre got things exactly wrong; when he said that Hell is other people."
Rather: Hell is what you get from having Sartre's conviction that Hell is other people. Hell is a consequence of souls who regard other people merely as instruments or obstacles to the assertion of one's own Self; who regard 'other people' as objects to be manipulated or eliminated as required to attain one's own goals; and this attitude is itself a product of the rejection of Love.
Heaven is essentially a family; and for a family to work - all of its members must be loving of each other. Any one can opt-out of family, reject family, unilaterally; but sustaining family requires mutuality.
This shows, in microcosm, the sense in which Heaven is difficult, and Hell is easy.
But when Heaven does happen (which it can, since the work of Jesus Christ has - by resurrection - made possible a permanent and eternal commitment to Heaven); then the possibilities are open-endedly expanding.
Heaven will spontaneously increase, will develop, will create - without limit; because in Heaven creation is mutually-reinforcing and cumulative - because Love feeds on itself, nourishes itself.
However, in Hell the opposite is true: Pride feeds upon itself; Pride increases at the expense of everything-except My Self.
The long-term tendency in Hell is towards rejection of cooperation, towards solitude; thus towards diminution.
In The Great Divorce, CS Lewis depicts Hell as a place where everybody tries to get-away-from everybody else; by spreading-out, locking themselves in and others out; by socially-distancing.
Lewis's Hell spreads-out even as all human interaction breaks-down. Men contract and repel, thus Hell spreads.*
This contraction of Hell to self-isolated and mutually-hostile souls happens as a natural consequence of increasing Pride: Self-assertion, self-ish-ness, and ever-more immediate short-termism... all these ensure that life trends-toward a continually-escalating conflict of each against all.
*However, in a Hell ruled by Satan; the population who crave self-isolation would be prevented from spreading-out; and would instead be forced-into close proximity in over-populated cities; in order to torment them further. And this is indeed the Global Establishment's plan for planet earth.
Note: By no coincidence; we can perceive an earthly approximation towards Hell in the global developments of 2020: towards a world of self-asserting, resentment-driven, mutually-hostile individuals - each of whom increasingly regards himself as a victim of the prejudice and selfishness of others. A world that regards other people as threats and obstacles. A world of physically-distanced and identity-obscured solo-individuals; fighting (hopelessly) against overwheling impersonal tyranny by asserted entitlements and 'rights'. A world demanding to 'use' others and their lives to extend my personal survival. Here in the UK millions of people are currently legally consigned to the literally-Hellish state of 'self-isolation'; characteristically (fiend-ishly) presented (by our inverted morality) as a public duty, for the 'protection' of others. PSYOPS...