I have often noticed that there is an almost-opposite stream of therapeutic self-help to the oneness spirituality - and that is to propose that we need to improve our powers of mental concentration.
This suggestion goes back to Nietzsche, and includes George Bernard Shaw and Colin Wilson - and also several strands of the Golden Dawn tradition of ritual, or ceremonial, magic*. All these (and many other self-help gurus) advocate training oneself (or undergoing systems of training) in 'habits' of mental control and concentration; as a kind of amplification of will power.
This is a significant half-truth; because there is certainly a sense in which our inability to control our thinking is a real plague of mind. If we cannot focus, or concentrate, our thoughts - then we can't follow a line of reasoning, cannot analyze and critique, cannot resist the ubiquitous distractions of mundane life (especially now that the mass-social media is so prevalent).
Also; people who have high powers of concentration - whether spontaneous or trained - may be impressive in their capacity for work, and also relatively socially dominant: they may be able to manipulate other people more effectively than would otherwise be the case, in a kind of "hypnotic" fashion.
Concentration really can, therefore, be a kind of power - power over the natural world, and over social situation, and it is easily understandable that some people (at least in some moods) would desire this power.
Yet such power amounts to self-assertion. It is a means to the end of imposing one's will on the rest of the world.
In other words; concentration operates at the level of the everyday, mundane self - which self is ultimately passive, externally-controlled, un-free.
What concentration bypasses is the Primal Self; and if you agree that this mortal life is "about" the learning and development of our Primal Self - then it can be seen that a focus upon focus, concentrating on concentration, is missing the point - and indeed amounts to a deliberate exclusion from purpose of the real meaning of life.
In other words: because a focus on concentration is a means, not an end; then, to the extent that mental concentration is made a purpose in life - in making concentration our aim we are not discovering (leave alone following) the divinely-intended destiny of our spiritual life.
Thus, to focus on enhancement of the will-power of concentration, is rather like making improved efficiency the goal of life while neglecting what the efficiency is aimed-at; instead of discovering what ought to be the purpose of life.
Overall it is surely better to be inefficiently aimed at the right purposes of life, then to focus efficiently on achieving goals that have been passively absorbed from external sources.
At root, a person with tremendously focused will power is not even serving his own interests - because the mundane self is not Primal nor essential, but merely contingent. In practice; will power operates as merely an effective servant of the powers that dominate this mortal world and life.
The lure of successful self-assertion, of imposing oneself upon other people and upon Life; in practice turns people into mental slaves for this-world's demonic rulers.
*An example of the power of trained "magical" concentration in the Golden Dawn tradition can be seen with the Inkling Charles Williams; of whom many accounts have been written of his hypnotic, charismatic effect. None more vivid than that of Lois Lang-Sims; who was an initially-complicit "victim" of Williams at his most "vampiric". Charles Williams demonstrates that a training in focused attention is a tool that can be effectively deployed - for good and Christian purposes; for the "Left Hand" path of selfish personal benefit - or for both purposes, at different times. Williams was aware of the temptations of such self-willed power, as is evident from several of his novels; yet despite such knowledge was not able effectively to resist the temptations to abuse such power - even in the last years of his life.