Patanjali's yoga sutras

ततः पुनः शान्तोदितौ तुल्यप्रत्ययौ चित्तस्यैकाग्रतापरिणामः॥१२॥

3.12 tatah punah śātoditau tulya-pratyayau cittasya-ikāgratā-parināmah

tatah = then

punah = again

śānta = that which has been subdued, the past

uditau = that which has arisen, the present

tulya = equal, the same

pratyayau = thoughts, content of the mind

cittasya = of the mind

ekagrata = one-pointedness

parināmah = transformation

Until you reach that ultimate state, start each practice with a decision to focus and not be distracted. When an equal amount of time is spent distracted and focused, know that you are in the transition to one-pointed focus.