the amount of time i spend drawing usually ends up being a matter of headspace, energy and level of motivation so i can have days where i really wanna draw but nothing comes or i'm finally able to draw but i'm too tired to get things started or finished
what's helped during recent bouts is just getting sketches out, doesn't matter for what but just something to get back into a rhythm and to remember the feel of drawing and then finding focused subject to work on after that, like roughs for comics, character drawings, etc
another thing i've learned recently is how i've likely been tackling warm up wrong or at the least wasn't fully informed of how to go over them and this tumblr post happened to be really useful in elaborating
i also second any advice on stretching between and during your sessions as well as properly hydrating but when it comes to setting a mood or building an environment to encourage creativity consider what things help put you at ease and help you feel productive and if you can't find another person to be your motivator find things you can reward yourself with like food or watching an episode of your favorite show. Beyond that is just building that space whether it's opening a window to let in fresh air or more light, putting on music that inspires your imagination or clearing out a space so you can 100% focus on just art without other distractions (even i've had to hide games or my phone from myself)
Plus like the little bird said there's always just stepping away and taking a breather, after all you can't always force creativity and in some cases can definitely do more harm than good