I'm basically paraphrasing @theproductivityzone here, but there are legions of us who have learned this through experience, so I expect we're all somewhat repetitive:
Pick a time, and stop. As mentioned in previous posts, it can be easy to let our work demands overtake other life considerations. But you are only as good to your work, your clients, your vocation, as you permit yourself to be. Work / life balance. Regenerate and recharge.
I take a minute or two to make sure I've wrapped up loose threads, including my desk. It can be easy to flee the day's work flow, but your next day will be immeasurably improved by making sure you've prepped your work space for the following day, rather than leaving it to be tackled in the morning. Just one or two minutes at the end of the day of looking at what needs following up works much better for me than trying to sort it out the following morning. It also gives me the peace of mind to detach.
And really: detach. If you are in full or semi work mode all the time, you're not at your best. I will check in to my phone occasionally and acknowledge receipt of an issue (VAs are never entirely shut down). But 95% of issues can not only wait till the following day, but are more successfully tackled then.
Let go. Turn it off. It will be there, and handled more efficiently, tomorrow.