Very simple. As the achievement suggests, In the top left of your screen you should see your "Damage" and "Collection" rates. All you need to do is have your mountaineers at the top of the "Collection" graph. As this graph is calculated over the course of a small time frame, setting your runners to rest (With breaktime or the break setting in "The Express" Building if you have already purchased it) will eventually remove them from the graph and letting your mountain climbers do their thing. It is recommended you attempt this achievement before purchasing any Zygnorps (From "The Academy") but it can be done if you have a low amount of them. It may also be wise to destroy any drones you may have by clicking them.