There are too many unknowns to control the future, but that does not mean we do not play a role in creating it. Anyone involved in a situation impacts it.
We have the most control over ourselves, but it is not always easy to understand our influence since we impact every situation we experience.
Start simple. If something does not go the way you want it to ask: “What could I have done differently.” Maybe the problem was entirely due to someone else (she was late), but there is almost always something you could have done to change the outcome (send her a reminder).
You cannot control everyone else (life wouldn’t be very interesting if you could), but if you are unhappy with something pay attention to what happened. Next time play a different role targeted at creating the result you want. If you do not know what to do differently, ask.