A lifestyle blog is a blog that is about the lifestyle of the blogger and their readers. This could be anything from cooking to fashion to travel. A lifestyle blog can be either personal or professional. A personal lifestyle blog is written by a person who is living their life the way they want to live it.
This could be a regular person who just happens to blog, or it could be a celebrity or professional who blogs about their life and how they live it. A professional lifestyle blog is written by someone who is in the business of helping people live a healthier lifestyle. This could be a personal trainer, nutritionist, or doctor.