Ken Grimwood

Jeff Winston was 43 and trapped in a tepid marriage and a dead-end job, waiting for that time when he could be truly happy, when he died. And when he woke and he was 18 again, with all his memories of the next 25 years intact. He could live his life again, avoiding the mistakes, making money from his knowledge of the future, seeking happiness. Until he dies at 43 and wakes up back in college again...