have a life

I scheduled a meeting with a client for 8:00 one
morning. I called the day before to confirm the date and
time. When I arrived at the client’s office the morning of
the meeting, he looked puzzled. “What are you doing here?
Didn’t you get my message?” he asked. Here’s what
happened: My client worked late the evening before trying
to prepare for our meeting. Realizing he wouldn’t be ready,
he sent me an e-mail at 8:30 p.m., telling me that we
needed to reschedule. I have a life, and I usually don’t
read e-mails in the evening. If he had called, I would have
known not to show up. This is a classic case of someone
sending an e-mail without thinking of the best way to
deliver the message to the reader.

What does 'have a life' mean?