汉朝有一位名叫马援的壮士。
他从小就有远大的志向，想做出一番事业来。
马援很聪明，他知道很多知识，还擅长武术。
长大后，他真的成了一位郡都邮官。
西汉末年的一天，马援接到命令要押送一批囚犯到别处去。
半路上，他看到囚犯们痛苦哀号的样子，心里很难过。
于是，他私自放了他们，自己逃到了北方。
后来，虽然皇帝赦免了他的罪行，但马援还是留在北方放牧。
他养了几千头牲畜，赚了很多钱。
他说：“一个真正的男子汉应该在困难中更加坚强，年纪大了也要保持强壮。”
他把赚来的钱分给亲戚朋友，自己只穿破旧的皮袄。
后来，马援投奔了武帝刘秀，在东汉成为了一名大将。
他立下了很多战功。
有一次，洞庭湖地区发生了动乱，武帝派人去征伐，但是全军覆没，没有成功。
马援知道了这个消息，就向皇帝请求带兵出征。
但是皇帝说：“你年纪太大了吧！”
马援回答：“我虽然六十二岁了，但我还能穿上盔甲骑上马，不能算老啊！”
于是，他穿好盔甲，一跃登上了马鞍。
皇帝看了，称赞道：“这位老人家真是老当益壮啊！”
于是答应了他的请求。
从那以后，“老当益壮”就成了用来形容年纪虽大，但志气豪壮的成语。
In the Han Dynasty, there was a brave man named Ma Yuan.
He had great ambitions from a young age and wanted to achieve something great.
Ma Yuan was very smart, he knew a lot of knowledge and was also good at martial arts.
When he grew up, he really became an official in charge of a county.
One day at the end of the Western Han Dynasty, Ma Yuan received orders to escort a group of prisoners to another place.
On the way, when he saw the prisoners moaning in pain, he felt very sad.
So he secretly released them and fled to the north.
Later, although the emperor pardoned his crime, Ma Yuan still stayed in the north to graze livestock.
He raised thousands of livestock and earned a lot of money.
He said: 'A real man should be stronger in times of difficulty, even if he gets old.'
He distributed the money he earned to relatives and friends, and himself only wore tattered leather coats.
Later, Ma Yuan joined Emperor Wu of the Eastern Han Dynasty and became a great general.
He made many military exploits.
Once, there was chaos in the Dongting Lake area, and the emperor sent troops to suppress it, but they were all wiped out without success.
When Ma Yuan heard this news, he asked the emperor for permission to lead troops to fight.
But the emperor said, 'Aren't you too old?'
Ma Yuan replied, 'Although I am 62 years old, I can still wear armor and ride a horse. I cannot be considered old!'
So he put on his armor and leaped onto the saddle.
The emperor looked at him and praised, 'This old man is truly old but strong!'
And agreed to his request.
From then on, 'old but strong' became an idiom used to describe someone who is old in age but full of ambition.
