When feeding treats, I ask the horse to take a step back before I feed the treat - I'm not interested in being mugged. When feeding hay or grain where I'm in the stall or paddock with the horse, particularly with a horse that is greedy about food, I ask the horse to step back before I feed, or in the case of a horse like Charisma who likes to lunge for her food and is exceptionally greedy, I ask her to take two big steps back and turn her head away. If I'm in a stall or paddock with a horse, I'll ask them to move away if I need space to do things. These things are so automatic with the horses and me now that usually I don't even have to do anything to ask for the step back or away, I just wait and they do it all on their own.
I also use one step back a lot when taking the horses out to turnout. I'll use it if they seem anxious when standing in the open stall door while I'm haltering. I'll often use it with a horse as they're in the barn aisle and ready to go - one step back and then we go. Sometimes I'll combine this with a head-down with a horse that seems excited. This reminds them that I'm there and will be asking for them to follow my directions, and also immediately introduces some softness into the situation. I'll use it at the pasture gate if a horse is thinking about rushing. Whenever I use one step back, I try to be as quiet and soft as possible, and I focus on the feet, and the movement of the feet, not the head of the horse.
I'm grateful to Tom Widdicombe and his book for reminding me of how important one step back can be.