I got this format for a personal mission statement from a Joe Rogan guest I listened to a while back. It's basically just a good outline you should look at. I haven't seen it in a while, I guess I need to make it a habit.
What is important? I value my wife, my few close friendships, my closest family, and my independence. I purposefully leave time open so I can be there for people I love and so I can choose to do what I want without many restrictions each day.
Where do I want to go? I want to continue learning healthy coping mechanisms regarding my mental health, stay married to my wife happily, and learn to be much more happy with my life in general. This will enable me to develop my personal skills, hobbies, and interests, like system administration, writing, and hopefully get into running my own business.
What does "the best" look like for me? To consistently attend doctor's appointments, maintain a stable relationship with my wife, keep the house clean and organized, spend time with friends and family, and be in healthy physical condition.
How do I want to act? I would want people to describe me as a kind leader who is intelligent and thoughtful. I want to be known as reliable. I want to be known as someone that people would want to rely on.
What kind of legacy do I want to leave behind? I want to influence people in ways that they will remember me being a pivotal character in their life story because of that influence. I want to actively be an important person in other people's lives.
Hopefully this influences someone else to do the same.