Inspired by path integral molecular dynamics, we build a spin model, in terms of spin coherent states, from which we can compute the quantum expectation values of a spin in a constant magnetic field. This formulation facilitates the description of a discrete quantum spin system in terms of a continuous classical model and recasts the quantum spin effects within the framework of path integrals. In particular, it allows for a much more direct path to the low- and high-temperature limits and to the definition of effective classical Hamiltonians. In this formalism, the quantum properties of the spins are described through an effective anisotropy. To check this, we solve the effective classical model using atomistic spin dynamics, we calculate thermodynamic observables and show that our effective classical models can reproduce accurate quantum expectation values within the relevant temperature ranges.