Some people say that promises are made to be broken. That certainly seems to be true in this cutthroat society that we live in. But if you break your promise, you will ruin your reputation and no one will trust you anymore. So whenever we say, "I give you my word," we should mean it. There is nothing worse than to be let down by others because they have not kept their promises. 

In fact, it isn't so difficult to keep promises. Just remember never to promise anything we are not sure we can live up to. In short, therefore, to be trustworthy, we should always say what we mean and mean what we say.

(You should) mean what you say  说话算话
make/keep/break promises
in cutthroat society 竞争激烈的社会    competitive 竞争的    to compete with others
ruin/destroy one's reputation
give you my word = Don't go back on your word   word不用复数  words吵架    promises 可用复数
let down = disappointed  失望
as a matter of fact -- in fact
live up to 做到    live up to one's expectations(永远用pl)达到某人的期望