'Watch ye and pray, lest ye enter into temptation. The spirit truly is ready, but the flesh is weak.'
Mark 14:38
Temptation is linked directly to what we think upon (Heb. 11:15). Temptation has to be entered into. We can avoid temptation by avoiding thoughts that generate temptation (Prov. 23:7). Since it is impossible to not think, we cannot just try to reject the negative thoughts in this world, but we must choose to think on the positive truths of God. This is where prayer comes in.
In prayer, we have our minds stayed upon God and therefore, are not receptive to thoughts that conceive temptation. Temptation or sin must be conceived (Jas. 1:14-15). In the physical realm, the easiest way to avoid an unwanted birth is to avoid conception, so it is in the spiritual world.
It is easier to avoid being tempted by being in constant communion with God, than it is to overcome temptation once it has been conceived.
Paul admonishes the Philippian believers to reflect and meditate upon eight positive principles of thinking that will lead to a victorious Christian life (Phil. 4:8). These are things that are 'true,' that is: honorable, truthful and upright. Things that are 'honest,' that is: honorable, truthful, genuine, not characterized by deception or fraud. Andrew Womack