The Buddha describes the four right efforts concisely and precisely.
Padhāna sutta - Striving
"Bhikkhus, these are the four right efforts. What four?
Here, bhikkhus, a bhikkhu produces a wholesome motivation, exerts effort, initiates and sustains energy, uplifts the mind, and strives to prevent the arising of unarisen harmful and unwholesome qualities;
He produces a wholesome motivation, exerts effort, initiates and sustains energy, uplifts the mind, and strives for the giving up of arisen harmful and unwholesome qualities;
He produces a wholesome motivation, exerts effort, initiates and sustains energy, uplifts the mind, and strives for the arising of unarisen wholesome qualities;
He produces a wholesome motivation, exerts effort, initiates and sustains energy, uplifts the mind, and strives for the stability and retention, growth and full development of arisen wholesome qualities.
These, bhikkhus, are the four right efforts.
Those who develop the right efforts overcome Māra's realm, they are detached and have crossed over the danger which is birth and death; They are content, having conquered Māra with his entire army, and are unshakable, having gone beyond all of Namuci's forces, they are truly at ease."