I did a bit of thinking on this prompted by the Daily Stoic journal. It made me realise that most, if not all of my annoyances stem from my weaknesses, not from external pressures.
In our modern lives, the things that annoy us are insignificant when compared to the real pressures of natural selection that our species had to face tens of thousands of years ago. But due to the fact that we are not adapted and trained to respond appropriately to modern stressors, we overreact. When the Wi-Fi dies, we get frustrated. When a guy cuts us off in traffic we start swearing and get angry. If a plane is a few minutes late we scoff in disbelief.
Due to our nature, emotions will arise in such situations. But we must not create feedback loops that amplify these and give them more weight than necessary.
Most times, we are only doing ourselves a disservice by getting annoyed. We should train ourselves to see mishaps as natural and inevitable. Notice them, make the appropriate rational decision about what to do next, and go on living well.