You can't really know yourself. Your whole brain is working all the time but you can only access parts of it. The rest is unconscious. So, there are limits right from the beginning. In addition to the impossible part of not ever getting directly to some parts of yourself, the conscious part censors, redirects, masks and hurries past parts it can sense you don't want to face. That makes a whole sector of suppression that you often don't want to admit and consider. That is the part where you have stuffed the notions you could think about but reject, the ideas that you are deeply flawed, would have been better if you hadn't done some things and if you had studied harder, blah, blah and et cetera.
The Buddha founded his thought on four noble truths:
Life is suffering
Suffering comes from grasping
Grasping for this and that can be avoided
The path to the avoidance of grasping can be found and followed.
These ideas can be quite different depending on the culture and society in which they are applied. It seems quite useful to me for most Americans to read American thinkers or those quite familiar with typical American ideas and ideals since some traditions picture a very ascetic application of them. One way of feeling the difference between an older and more current application is to consider the term "householder". Not a word one hears in religion talk much but it can be contrasted with "devotee" or "monk".
These ideas can also vary by origin and country. They originated in India but in Chinese or Japanese or Korean versions, they can differ. The American Stephen Mitchell and his wife, Byron Katie, are sources of applied versions that seem to me to apply well to American lives.
The Buddhist nun Pema Chodron, a grandmother and former American school teacher, often summarizes the application of the ideas as "don't run". She means face the pain, the loneliness, the fear of oblivion or poverty or whatever. She counsels looking at one's feelings and just seeing. If I am having a down day, if I am afraid of having a colonoscopy, if I am ashamed of my wrinkles and my limp, a good start would be noting all that. Maybe writing down what I fear and what comes to mind about these things.
A counselor or a friend or me by myself can just look at the fear. Observe it. Maybe try a little questioning of it: how long have I had this fear? What happens next? Can I be proud of my flaws? Have they helped me? Who would I be without them? If I lost them, would I miss them? Can I draw an image of them? Are they gifts?
You might get to the place where Byron Katie was when she said at age 63, "I am having the time of my life watching my body fall apart." I admit that in today's world, 63 is rather young. You might not begin serious aging until 20 years later. You might develop sympathy for the Jack Ziegler cartoon of 1992: "Say, this isn't so bad."