Mechanical Weathering isn't always good sometimes it can harm us and the things around us.
The things that mother nature uses are wind, water, ice (glaciers), and abrasion.
Like for example Ice can break rocks when it reaches it freezing point how? it hits the rock and starts breaking it, and Abrasion is when two rocks hit each other, wind can do the same thing by throwing sand and a rock at each other, water can also make this happen when the water moves the rocks and they hit each other or by being scraped on the bottom of the ocean.
These are the resources that Mechanical Weathering use to break rocks in there own ways.