Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy strength, and with all thy mind

Luke 10:27: And he answering said, Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy strength, and with all thy mind; and thy neighbour as thyself.

Thou shalt love the Lord, thy God is the first duty of all God's creatures. He is worthy of love. He is lovable and attracts love. As soon as a right-minded person sees God as he is, especially as revealed in Jesus Christ, he is drawn to Him. This love is also the best, the noblest, the most elevating, purifying, enlarging act of the soul. 
With all thy heart. Heart denotes in general terms the affect and will; affectionate choice, "the love of conscious resolve, expressed with will, which must at once become a second nature.. The heart is the center of all physical and spiritual life, the soul or mind, as it is the fountain and seat of the thoughts, passions, desires, appetites, affections, purposes, endeavors." 
And with thy soul. Soul is the individual existence, the person himself, the seat of the will, dispositions, desires, character. The two words are united to teach that the entire undivided person must share in that which it has to perform with the heart. the soul according to Jesus, is a man's inmost self; the seat of his conscious personality, inherently immortal, precious beyond all price. 
With all thy strength. The whole power of the man must go into this love. Not only the heart, but the most intense power of all the heart. Not only the whole mass heated to the highest degree. Not only  all the soul, but all of the soul at its strongest and best. The greatest momentum of a body is made up of the whole mass moving with all the velocity of which it is capable. 
With all they mind. True love has its intellectual and reasonable side. It is not blind. And love always exalts the mind, enlarges the intellect, and stimulates thought. 
And thy neighbor as thyself.  This is the principle in the heart from which flows the Golden Rule in practice, and perfect keeping of all the commandments which refer to our duties to our fellow man. Love is fulfilling of the law.