This is the reason for the advice 'Forget the past, give up planning for the future, live in the solid present'. This is again the basis of the declaration that real Tyaga lies in the renunciation of Sankalpa-Vikalpa. You must set up a guard over the mind. There must be continuous discrimination and firm checking. Vichara and ready 'Nirodha' should never be stopped.
Man is usually lazy and unwilling to take up the important task.
Moreover vanity also is at the back of this reluctance to employ this inner method of restraint. Because this is purely a subjective, inner training. It does not get advertised and acquires no publicity. Whereas physical austerity and forcible methods appear heroic for all to see and admire. This vanity is very subtle and not realised easily.