"have a great day" is a friendly wish for someone's day to go well. It's often used as a polite farewell in conversation, emails, or customer service.
Events like this mean we can give something back to the people that support us, and hopefully everyone will have a great day and we can put on a good show for them. Nelson Piquet
If you have a great day at work and you've been hit with all these great ideas and there's a lot of excitement on your team, your mind doesn't turn off. For years I've kept a pad of paper and pen by me at night, because things just occur to you. Anne Sweeney
Sometimes I have a great day of filming and sometimes the theater strikes me better. It just depends. Philip Seymour Hoffman