Need positive thoughts

Here is what happened:
The practice manager at my work place (not my employee) dropped the ball on a task that needed to be done. She had been reminded numerous times but didn’t complete the task and did not get the help needed when she did not understand the task. I ended up completing
it today but it was not what I had planned in my time management.
What is a thought I can have that maintains a growth mindset? When is it ok to be disappointed or angry?
How do you account for unplanned urgent activities in your time management plan?