It means you will do what you say. You will show up when you promise. A life built with integrity has a firm foundation and will reap the rewards of trust. Build upon loose morals and your house will not stand.
Recommendation letters don't get written for scoundrels. Saying the end justifies the means loses its potency when done over and over again. Your dealings with people, the care, or hurt you inflict will catch up some day.
They say to be careful stepping on others to reach the top, lest you fall and no one be there to catch you. Personally, I much prefer to build something with others rather than on top of them. A trail of mistrust and betrayal does not make for a firm foundation. Only integrity can hold the weight of an empire once fully realized.