"It is to worship God as though you
see Him, and while you see Him not truly He sees you"
(Saying of the Prophet, pbuh)
The meaning of Ihsan is to do things in the best of ways, to perfect all acts of worship and to perform them as we were commanded to do so, whilst observing the rights of God within them. It is to be vigilant with an awareness that God is watching you. It is to have the presence of His greatness and Majesty in your heart, and in doing so to have a present heart.
Ihsan is thus a means through which, in worshipping your Lord as if you see Him, the servant is able to perfect his worship. For if you were to see you Lord before you, your performance would be to the best of your ability, with much greater care and attention being given to both your inward and your outward actions, attempting to perform them in the best of ways. As for the statement, 'if you can't see Him, then know that He sees you'. What is indicated here is that although a servant cannot see his Lord either way God, Most High, can see Him and "He is," as the Prophet (pbuh) has said, "in truth present in the qiblah of everyone of you."
The state of separation in which we live is due to the veils which hide Him from our sight; but even in apparent separation we are never alone or unobserved; He sees not only our every action but our every thought; He is al-Khabir, the Totally Aware, from whose all-embracing consciousness nothing is hidden.
Thus ihsan should not stop at Prayer or other ritual acts or of worship, it implies seeking perfection and striving for excellence in everything you do, allowing it to permeate your every action. It implies therefore, being always conscious of your responsibilities before God and striving hard with all resources to fulfil these obligations. It is the epitome of sincerity. For to worship God as if you saw Him is to worship Him sincerely. Thus if ihsan, 'perfection', which can also mean beauty of the soul or heart, permeates the inward, it will necessarily emanate outwards, transforming every human activity into the remembrance of God. One who acts in this fashion is described as a muhsin.
Allah has required ihsan from all his servants and in everything they do, as has been related by the Prophet (pbuh) "Allah has written ihsan in everything..." So in this hadith there is an indication as to what purifies the acts of worship and draws you closer to Allah:
"Verily Allah loves the Muhsineen"
"Truly, Allah is with those
who fear Him, and those who are Muhsinun (those who have ihsan)"
<Quran An-Nahl 16:128>
So if the believer does not fall short in the first, to worship your Lord as if you see Him, he should not fall short in the second as in reality both are the same.
"In whatever activity you may
be, and whichever part of Quran you recite, and whatever deed you do [O Mankind],
We are witness over you when you are deeply engrossed therein. Not an atom's
weight in the earth or in the heaven escapes your Lord, nor is there anything
smaller or greater, but that it is [written] in a clear Book.
<Quran Yunus 10:61>
(Source: Habib Hussain bin Taher, Meaning & Commentary on the Hadith of Gibreel; Gai Eaton, Islam & the Destiny of Man; Syed Ali Ashraf, The Inner meaning of the Islamic Rites - Islamic Spirituality)