Depends on how the word "hard" is defined and used. Could be either: SOFT or EASY.
The opposite of "Push hard" or a hard push is an easy or light push.
The opposite of hard-working could be lazy, slothful, lethargic, or indolent.
Soft
easy
If you mean hard as in the opposite of soft, then rigid, firm, adamatine. If you mean the opposite of easy, then difficult
Hard
hard
hard
Soft means yielding readily to touch or pressure, easily penetrated or changed in shape. The opposite would be hard, solid and firm to the touch.
The usual opposite of facil (easy) is dificil(difficult, hard).
the Hebrew word for complicated or hard (the opposite of easy) would be: kahshe and hard (the opposite of smooth) would be the same.
The opposite of lazy would be industrious or hard-working.