How much personal conflict is in your daily life? Conflict in this example is when two (or more) people want different things.
In my life, conflict is a constant background hum. Let me give you some basic examples. What breakfast your child will have (you: oatmeal; them: jelly). Negotiating with a neighbour over essential drainage works (you: your buddy; them: cheapest quote). Talking with your friend about their deadbeat husband (you: leave; them: one last chance). And those are just the big ticket conflicts. There are countless micro conflicts like changing lanes in traffic.
Through these minor and not so minor conflicts, I’ve encountered some fascinating personalities, perspectives and behaviours. What people want is governed by a cornucopia of factors. Motivations and emotions can change from moment to moment. They may not even be relevant to the situation at hand (eg, deep seated grudge? fatigue? lack of time?). That is before exploring personality and life experience.
Instead of allowing these daily conflicts eat you up, why not let them inspire you? Often the behaviour you see needs no embellishment: real people are more complex than your characters could ever hope to be.