Don’t let bad behaviour slide. If someone is rolling into work late repeatedly, you can say, "Just so we are clear, don’t mistake my kindness for permission to underperform at your job. You need to be on time." This shows that you’re not afraid to step up and own your niceness instead of apologising for it, while being direct with feedback. Stress the fact that this is a trusting relationship. If someone needs to leave early or has to arrive late, you trust that they will still get their work done. But you also trust them to communicate schedule challenges with you. Use the opportunity to find out if something else is going on causing the need for a shift in schedule (empathy + authority).