I would add, that you cannot expect yourself to focus on a task, where the benefit in investing your precious time in it does not outweigh the mental effort in it. The benefit can either be a growth and increased interconnection of your own organic neuronal network, i.e. learning a knowledge-item, which helps you to later solve tasks, which will again lead to benefit. Or the benefit can be based on purely materialistic/monetary aspects, i.e. ensures your survival. The benefit could also be of karmic nature, meaning that you help other people in gaining benefit, which will usually reflect back on you in the future as another source of benefit. So far to the dopamine-centered lifestyle we chose
(benefit can also be synonym to dopamine in most cases)
If the benefit level is not higher than the needed effort level, the task will cause an increased production of stress hormones and consequently an aversion towards the specific task, which will make concentration impossible. If you continue to try to focus on benefit free tasks, your terminal station willl be a burnout.
I can assure you, that you should either only seek tasks, whose solutions can be beneficial for you or work yourself towards a state (if it must be with artificial boosters like stims), where solving promising tasks without aid is possible.
Don't try to solve another ones bullshit (no benefit) if it is not absolutely necessary. If you do not believe in monetary wealth, then so be it.
And I agree to the above. Meditation aka "being awake and aware without focus in silence" regularly is important.