Effective parameters can be subtle, but they are always clear. For example, when a coworker flirts with you, think about whether you want flirting to be part of that relationship (definition). Then, give them clear signals (parameters) telling them whether or not you want flirting to be part of that relationship. Or... when a friend is not spending as much time with you as you would like (definition), let them know that you miss them and would like to see them sometime soon (parameter). If they are not available on an ongoing basis, you can redefine that relationship to more of an "acquaintance", and seek a new friend to meet your friendship needs.
By setting parameters, both people than know where they stand with each other. This leads to trusting the relationship and trusting each other. It allows us to get what we want most from the relationship. Defining our relationships and setting parameters to maintain them lays a foundation for them to go deeper and to be more fulfilling.
Defining relationships and setting parameters requires a lot of work. Definition requires thought and difficult decisions. Setting parameters requires courage and strength to address awkward and difficult situations. And... we have to pay attention. But sooner or later, we have to ask ourselves, "Just how important are our relationships to us?"