Stocking up on vitamin C
Scott Lang (or Ant-Man) is one of my favorite characters in the Marvel Cinematic Universe. He approaches the whole experience with an irreverence that helps to make harder moments in the films that little bit lighter. He’s also pretty smart and learns quickly from his mistakes and experiences. Like the first time, he grew to a giant.
After his pretty traumatic experience in Captain America: Civil War, which he cured with orange slices we hear this referenced in Avengers: Endgame. Right after Clint (a.k.a. Hawkeye) returns from time-traveling, Scott gives him an orange slice. He obviously knows this is a good cure for a weird molecular experience!