Since you can't (and don't need to) remember everything, you should prioritize your mental space and use shortcuts to help you remember things you don't need to memorize. Writing things down is an important way to ensure that you don't miss appointments, forget medications, or other important things that you can't risk forgetting.  Try keeping Post-it notes or a white board in the office with daily tasks and reminders.  Use a calendar or planner to keep track of important upcoming events and deadlines, and keep a running shopping list to take to the grocery store. Repeating things you are told can help to fire pathways in your brain to ensure that you can remember it better later.  When you meet someone new and they introduce themselves, repeat their name right then, and again at the end of the conversation. You can do it casually: in the beginning of the conversation, say, "It's so nice to meet you, John." Repeat again at the end of your conversation, "It was great talking to you, John." Repeat important instructions from your doctor, and if needed, write them down to ensure you remember accurately. By learning to calm your mind and focus your attention, you can improve your mental clarity which has positive effects on your memory and attention span.  In one study, participants who practiced mindfulness for 20-30 minutes daily scored better on standardized memory tests than those who took a nutrition class. Mindfulness is a meditative practice that involves sitting and breathing slowly while focusing on physical sensations such as your breath moving in and out. Try to meditate twice a day for 10-20 minutes at a time.

TL;DR in Vietnamese:
Viết các việc cần thiết ra giấy. Lặp lại các chi tiết quan trọng. Tập thiền hoặc yoga.