You blow dry your hair, lifting the roots with a round brush, but after an hour they fall hopelessly. Sound familiar?
This is because you are breaking the laws of physics and aerodynamics. Hot air directed from top to bottom presses the hair against the head, depriving it of volume.
How to fix it? Literally flip over! Wash your hair leaning forward and blow dry it with the air flow directed upward.

This will lift the roots and create a “volumizing” effect that will last all day. Another fatal mistake: combing wet hair. Wet fibers stretch and break, which leads to split ends.
Instead, gently blot them with a microfiber towel and apply a leave-in treatment, starting from the ends.
For maximum volume, use mousse or foam, but apply it ONLY to the roots - otherwise, your hair will become heavy.
And to keep your hairdo for the second day, before going to bed, braid a soft ponytail on the top of your head using a silk elastic band. In the morning, let your hair down, fluff it up a bit with your fingers – and the volume at the roots will surprise you.
After a week of such experiments, you will understand how you lived before with flat strands. And yes, do not wash your hair every day - this deprives it of natural oils.
Instead, use homemade dry shampoo: mix cornstarch with cocoa powder (for dark hair) or rosemary (for light hair) and brush onto roots.