  Motivated by recent experimental observations of coherent many-body revivals
in a constrained Rydberg atom chain, we construct a weak quasi-local
deformation of the Rydberg blockade Hamiltonian, which makes the revivals
virtually perfect. Our analysis suggests the existence of an underlying
non-integrable Hamiltonian which supports an emergent SU(2)-spin dynamics
within a small subspace of the many-body Hilbert space. We show that such
perfect dynamics necessitates the existence of atypical, nonergodic energy
eigenstates - quantum many-body scars. Furthermore, using these insights, we
construct a toy model that hosts exact quantum many-body scars, providing an
intuitive explanation of their origin. Our results offer specific routes to
enhancing coherent many-body revivals, and provide a step towards establishing
the stability of quantum many-body scars in the thermodynamic limit.
