To do anything by mental control is always difficult, when what is attempted runs contrary to the trend of human nature or of the personal nature. A strong will patiently and perseveringly turned towards its object can effect a change, but usually it takes a long time and the success at the beginning may be only partial and chequered by many failures.
To turn all actions automatically into worship cannot be done by thought control only; there must be a strong aspiration in the heart which will bring about some realisation or feeling of the presence of the One to whom worship is offered. The bhakta does not rely on his own effort alone, but on the grace and power of the Divine whom he adores.
Ref : Letters on Yoga Vol. III