Scott Lang is a quick-minded fellow who’s ready to dish it out. When danger comes knocking, he’s ready to face it head-first on a moment’s notice. In Avengers: Endgame, there’s a scene where Scott’s just chilling, looking about the birds that Thanos’ snap brought back when all of a sudden, the villain springs a surprise attack on our hero.
As the attack takes place, we can see Ant-Man shrinking. This impromptu trick was what helped him survive the blast. Although he was a bit worse for wear after the strike, his quick-thinking softened the blow.