"Whatever happens, conduct yourselves in a manner worthy of the gospel of Christ." Philippians 1:27
Actions are what we purposefully choose to do, and reactions are more of an attitude response with actions that demonstrate our response to the actions of others. Often the reaction is less pretty and even more intense than the action. In the 1980's I was involved in a building project in Mexico. I was in the mode and action of hammering nails. Well, you guessed it, I hit my fingernail instead of the metal nail. My reaction was "OUCH, PAIN, FRUSTRATION, and A DESIRE FOR RELIEF." I did let out noise. I called myself foolish, stupid, idiotic. I put my finger in ice water, and held it above my heart. It hurt. In the middle of the night, I ended up drilling a hole in my nail to release the pressure.
The key thought is that actions are a choice, and reactions are a choice. Our attitude is to reflect Christ. Yes we all have reactions that we aren't very proud of, maybe even ridiculous, silly, and uncalled for. Philippians chapter 2 says that "Your attitude should be the same as that of Christ Jesus." The point being made here is that our attitude is what's important. Our attitude should glorify God, pointing people to our admiration and desire to honor Him at all times. When something great happens after working hard - thank Him. When something wonderful takes place that was unexpected - thank Him. When we have a hard time with something and it doesn't go as planned - thank Him for the opportunity to learn and use our talents to honor Him. Actions and reactions are opportunities for us to remind ourselves who we serve and why we serve. It is about Him and not us. I once saw a bumper sticker that had two words - "JESUS" was in big letters and underlined and "ME" in small letters under the line. Get it "Jesus is over me" and my life is about conducting myself that way.