You probably feel like doing nothing. Staying in bed all day or curled up on a couch just letting time drift by.But it's the worst thing you can do. It doesn't make you feel any better.
Instead get yourself up and occupy yourself with something. Almost anything will do but preferably outside. Dig or hoe your garden if you're lucky enough to have one. Walk down to the shops and treat yourself to something really nice for dinner. Take a bike ride or go work out at the gym. Send an email or two to people you've been neglecting for a while. Or address some minor household chore you've been putting off for ages.
Anything but lying around doing nothing.
I'm not suggesting for a minute this is a cure for anxiety or depression. But it will help get you through the day and leave you feeling a lot better at the end of it rather than simply doing nothing.
Occupation is always good therapy.