Nuke your bread to make it last
Often, the excuse is "It's gone hard!" The reason why bread goes a little firm after two or three days is loss of water. A simple cure for that is to put the bread into a microwave oven for 30 seconds. The heat makes the bread absorb water from the atmosphere and it will be soft enough to be toasted.
If you want a hard crust on your old bread then put the bread into your oven alongside whatever else you are cooking. Don't waste gas on just a piece of bread.
You can also make breadcrumbs and use the crumbs in various recipes.
BBC - Why is bread Britain's most wasted food?