System: You Gave Me Gymnastics at the Beginning, and Then You Sent Me Through Time?

When Xu Huai, an ordinary office man, was forcibly selected by the system and given the first task, he would be ten centimeters shorter if he didn't do it, and the reward was only radio gymnastics that everyone knew how to do. Before he could complain, he was sent to another world and became a useless general of a country. There were so many people who wanted to kill him, but the emperor actually ordered him to fight all the way from the border back to the imperial capital. What should Xu Huai do? "System!! Why did you trick me again!!!"