One thing you can say is that as you matured, your priorities in life changed, and as you started looking toward the kind of adult life you wanted, you realized the importance of a career which allows you to spend holidays and the like with your family (be careful not to make it sound like you won’t work late if they need you to, but everyone understands the holidays!). The other thing you can do is to turn it back on the type of job you are applying for, making it clear why you found that so much more appealing. That not only shows enthusiasm for the job you are interviewing for and keeps you from having to say anything negative about previous jobs (always wise), but it makes it clear that you have looked into the job you are interviewing for.

Good luck!