i watched the passion of Christ today on good friday in church and that was the question that was going through my mind all the time.
the reason that He did that was because He knew what the cross meant to Him. He knew that the cross was the only way that allowed Man's redemption to God once again... He knew that the cross was the Father's plan, and that was the way that the Father had wanted Him to go through. He knew that the cross was that which He had came down to earth for, that it was only by the cross, that all that He came down for was to be accomplished.
He knew that He knew that the cross was that and more. the cross was the reason that He came and He had to embrace the cross that was the way that the Father made for Man's salvation.
He embraced it because of love. the love for all mankind. the love that He had for you and me since the day we were in our mother's womb. and it was that same love that held Him on the cross, the same love that reconciled both Man and God.