Virajya vishhaya-vrAtA doshha-dRRishhTyA muhur-muhuH /
svalakshhye niyatAvasthA manasaH shama uchyate // (Vivekachudamani: 22)
The conglomerate of all sensual experience in the form of sound, touch, form, taste and smell by the five sense organs is called *vishhaya-vrAta*.
By discretion (viveka) and dispassion (vairAgya) one has to analyse and discover that all these are only obstacles on the path to Self-Realisation and so we have to discard them. This is what is said by *muhur-muhuH doshha-dRRishhTyA virajya* -- meaning, ‘often, by realising they are bad, discarding out of disgust’.
Our mind is always thinking about what it considers pleasurable and is perturbed because of the inability to reach them. Thus it misses peace and happiness.
In other words the mind that is frantically running after multifarious matters can be made to stop that running and can be tethered to one goal. That kind of control is what is called *shama*.