We chart our lives as paths through multidimensional state spaces. It’s trivial of course to consider only the familiar four dimensions, but these diagrams only become meaningful when you disregard the relative simplicity of space-time and plot, instead, your position in decision-space.
You stand motionless at the vector sum of every decision you have ever made. Decision-space has a very high dimensionality, so considered freely there is a dizzying array of movements available from this position. You never choose freely, though, because too much freedom of movement invites paralysis. Instead, you filter your options through constraints.
The constraints in decision-space are as varied as the dimensions there. Suffice it to say only that they can be categorized by nature. Some are boundaries, limits; the things you will do, or will not; the thresholds you could only cross by becoming someone else. Others are somewhat softer: the things you should do, or should not, the violations of which are sub-optimal yet not redefining. The space remaining within these constraints is what we typically think of as possibility; it is what you may do.
Depending on your goals and your skill at navigating decision-space, an optimal path forward might be apparent. If we were angelic in nature, the optimal path would be always clear, and deviation would be impossible. This would be terrible.
Chess is not yet a solved game, but a solution has not been proved impossible. If it ever is solved, at every stage, there will be a single move known to be optimal, and only a fool would choose otherwise. You could look up every chess game from that point forward in a sufficiently large table. There would be no joy in it.
Life is interesting only because people keep going around making suboptimal choices. Somewhere in that angle between the constraints, people make their choices according to their nature and situation, and almost never choose optimally. The deviation between your optimal path and your own life is exactly what makes your life worth living.