As a general rule you can hold no more than three things in your head at one time.
You can try to deny this, but it’s easier to accept it, and learn to work with it.
Got too many things in your head? Get them out.
Need to remember something? Chunk it into no more than three clean chunks.
Juggling too many things to do? Pick the three most important, and update your list as you go.
Keep it to three, and your brain will thank you.