What's "over-extending" mean and is it commonly used?

Native speaker’s answer
Rebecca
To "over-extend" means to go over, or exceed the amount of work, resources, or obligations one can do. I'd say it's commonly said! You can even say it to friends and say, "don't over-extend yourself," to encourage them to rest and take care of themselves. Ex: Danny kept over-extending herself, so she became sick and fatigued. Ex: Don't over-extend yourself by working the whole weekend. Ex: We over-extended ourselves with the Christmas gifts this year.