The first agreement in the book 'The Four Agreements' by Don Miguel Ruiz is 'be impeccable with your word'.
He states that this is the most important agreement, but also the most difficult one to honor. Being impeccable with your word is tied closely to the second yama, satya (truth).

I think most of us believe we are truthful people, but when we dig a little deeper into our daily interactions we may notice that perhaps there are more untruths present than we'd expect.

Firstly look on the inside; are you impeccable with your word or do you tell yourself untruths like 'I'm not good enough to do …' or look at another person and tell yourself that they're prettier, luckier or more capable in some way than you are?
Do you tell yourself little untruths like you're not really addicted to sugar, that this one icecream isn't doing any harm, even though you say that every single day.
Do you tell yourself you'll start dieting, meditating, exercising or reading tomorrow but never get around to it? Do you do the things you tell yourself you're going to do?

As with so many of our yogic practices, we must begin on the inside before being able to practice in our interactions with others.

When we become aware of how many untruths we tell to ourselves it perhaps isn't surprising that there are untruths told to others. A little embellishment on a story here, an excuse for being late there….

In yoga we begin with awareness. Noticing when we do certain things and being an observer of our habits and patterns without any judgment on our actions or efforts. From that place of awareness we can set a new path.
This week, steer a course for satya. Be impeccable with your word. Remember to practice satya with ahimsa (non harming) and do not use the truth to hurt others. There is a delicate balance to this practice; it is not perhaps about perfection, but about reducing the unnecessary untruths that cause us stress and self-doubt.