Wouldn't you agree that our brains are just some sort of hoarder - years of gathering info on how to act, think, behave (why do knives always go to the right of the dinner plate??); what 'makes' our lives complete; what 'defines' us; how our job/possessions represent achievement; friends vs enemies vs frenemies!; and classifying ourselves by what we do and not who we are in essence (as opposed to how we wish to be portrayed)?
We seem to live a life of comparison to some unrealistic ideal lodged firmly in our heads from our very first breath - emulating and measuring expectations (and biases) of parents, peers, social circles, and anything that we fear may pass judgement on the 'correctness' of our presence. Even those who buck the system are merely creating a predictable stereotype to the same end.
My advice: LET IT GO! We belong for no other reason than that we are here. If not so, then it would not be so.
In most cases the issue can be looking too much back at ourselves - critically running events through this rather clogged filter of behavioural appropriateness to soothe/satisfy the conniptions of others (who are no doubt doing exactly the same thing).
We are only ever this moment in time and the one constant is change - erosion, degradation, subsidence, climate, evolution, and the very cells in our bodies - we live in a state of flux on a planet in perpetual motion. The one assurance being that everything that is, although undergoing several transformations (and abominations), is as it should be, and accepting our association to this natural order can help us to understand it is not really our business to meddle, control, or take ownership of what is provided - so far, despite patting ourselves firmly on the back with our inventions, interventions, and aspirations, we have made quite a hash of it on the whole.
Mindfulness may be more about releasing ourselves from our thoughts - the ability to let things pass through instead of taking up residence only to veil reality or find ulterior motives.
Has no one observed how absurd the construct of life is? Surely you have felt it every day as you strive to find inner peace and synergy within existence and your place in it.
What thoughts/beliefs have you held so long and so dear that you can't even remember why? What can you dispose of in your mind that is just taking up valuable space, diminishing awareness, and bogging you down?