A general linear expression including all such effects is: d2x/dt2 + pdx/dt + qx = f(t)
d2x/dt2 gives the acceleration toward goal.
dx/dt gives the velocity of movement toward the goal--leads to SWB aka happiness (H).
x gives our current state vis-à-vis the goal.
f(t) is an external disturbance term that will push us toward or away from the goal.