Break up the sugar with a fork, spoon, or your hands
Place the sugar in an airtight container
Add a slice of bread to the container
Seal the container and let it sit overnight
Replace the bread if needed until the sugar softens
Add a few marshmallows to the container
Add a damp paper towel in a separate sealed bag or container for a short time
Microwave the sugar with a damp paper towel for a few seconds at a time
Warm the sugar in the oven at low heat for a few minutes
Store brown sugar with a tight seal to prevent hardening