The greek word for troubled as used in the scripture above is tarássō – properly, put in motion (to agitate back-and-forth, shake to-and-fro); (figuratively) to set in motion what needs to remain still (at ease); to "trouble" ("agitate"), causing inner perplexity (emotional agitation) from getting too stirred up inside ("upset").
What stood out to me in the definition is "to set in motion what needs to remain still (at ease)"
. I feel like God is saying that He doesn't want anything to stir me up on the inside. He wants me to inwardly remain steady and consistent. My "inside" should always feel peace and have a stillness. Even good things can stir us up too much on the inside upsetting the peace on the inside of us. I have learned it can go both ways. Exercising a little indifference to certain things, that come into our lives, might be essential to peace.