[Woe to the praying ones, who are unmindful of their prayers; who would be seen (at worship).] (Al-Ma`un 107:4-6)
That means that what makes our regular prayers proper is not the actual movements, for example, bowing, prostrating oneself, etc., but their aim and the kind of thought given to them. Some people pray just to show others that they are "Muslims," but instead of gaining ground with Allah, they are committing a great transgression.
What gives our prayers rectitude is our consciousness that we are prostrating ourselves before Allah only in order to express our devotion to Him. That is why Allah commands believers to [stand before Allah with devotion] (Al-Baqarah 2:238).
Another verse describes the believers as those [who offer their prayers with all solemnity and submissiveness] (Al-Mu'minun 23:2).
Solemnity in this verse means experiencing fear accompanied by deep respect and having one's heart filled with awe. Such a prayer increases one's faith and closeness to Allah. It keeps man standing firm.
In another verse regular prayers are described:
[Recite what is sent of the Book by inspiration to you, and establish regular prayer: for prayer restrains from shameful and unjust deeds; and remembrance of Allah is the greatest (thing in life) without doubt. And Allah knows the (deeds) that you do.] (Al-`Ankabut 29:45)