Many times I have heard it said that no one can keep all of the commands but, this is not true. From an Hebraic perspective of the word shamar behind the English word keep, it is possible to keep all of the commands. The problem lies in our understanding of keep as meaning obedience, but this is not the meaning of shamar. It should first be recognized that not all of the commands of the torah are for all people. Some are only for the priests, some are only for men and some are only for women. Some are only for children and some are for leaders. But, it should also be understood that even if a command is not for you, you can still keep it. The original picture painted by the Hebrew word shamar is a sheepfold. When a shepherd was out in the wilderness with his flock, he would gather thorn bushes to erect a corral to place his flock in at night. The thorns would deter predators and thereby protect and guard the sheep from harm. The word shamiyr derived from this root means a thorn. The word shamar means to guard and protect and can be seen in the Aaronic blessing, May Yahweh bless you and keep (guard and protect) you. One keeps the commands of God by guarding and protecting them.
AHLB# 2853 (V) / Strong's# 8104