Executive functions are those brain functions that we think of as "cognitive" or "thinking" related functions. Core executive functions are response inhibition, selective attention, working memory, and cognitive flexibility. Things like reasoning, problem solving, and planning are considered higher-order executive functions that build upon these core functions.
Executive functions are top-down functions, meaning that they require the prefrontal cortex of the brain to be active or "online" and require effort to perform. When you're dysregulated, your prefrontal cortex is offline and you can't expect yourself to effectively access your executive function in that state. It's neurologically impossible. Bringing yourself back to a regulated state will allow you to more effectively access your executive functioning skills.
Executive functions can be dynamic, meaning that some days (when you slept well, have eaten well, are generally well-regulated) you don't struggle with specific tasks, such as remembering a short grocery list. But if you're hungry, tired, and cranky, good luck remembering even one item on that list!
This is where self-compassion and accommodation come in. Practice being kind to yourself in the moments when your executive functions just aren't functioning well. It's not a reflection of how hard you're trying or how much you care, it's simply your brain struggling to execute these very complex neural processes. If you struggle with a particular type of executive function on a regular basis, think about the ways you can accommodate yourself to make things easier. Does a visual clock help you track the time? Would a large wall calendar or white board help you keep track of appointments? Would using the calendar and notes apps on your phone help? Do you prefer a paper journal or planner to jot things down before you forget them?
Be creative, check out social media for tips and tricks from other neurodivergent folks, or consider working with an ADHD coach to create strategies specific to you.