Vivian Creek Trail to San Gorgonio Vs Mount Whitney

I climbed San Gorgonio via Vivian Creek trail yesterday. Felt great the first 7 miles and then hit a 'major wall' at about 10,000 feet. I did persist and made it to the top, but all I kept thinking was "if this is hard going to 11,500, how am I going to do Mount Whitney which is 3000 feet higher?" Is this hike supposed to feel like a cakewalk before attempting Whitney?