More force is required to push a body than pull to get same speed on a ground with same friction. Why?

Force is required to lift a body from the ground to a height h and work is measured as the product of force and magnitude of displacement. A man of mass 60 kg carries a stone of mass 20 kg to the top of a multistoreyed building of height 50 m . Calculate the total energy spent by him? (g= 9.8 m/s^2)

An external force is always required to brake the inertia of a body which is either in the state of rest or state of uniform motion. Can all forces produce acceleration? Why?