The human soul or spirit is its center of energy, and it is strengthened by pleasant smells. So when you spray on some good perfume, or light up some incense,  or  even when you smell the aroma of brewed coffee or a well cooked meal, a glimmer of happiness creeps into your heart, and your spirit gets uplifted and re-energized.
The prophet Mohammed (PBUH) has emphasized his love of good perfume in several hadiths, from which I am going to list a couple.
"Allah is pleasant and loves pleasant things, clean and loves cleanliness, generous and loves generosity…”
 Sayyiduna Anas relates that, “The Prophet (PBUH) would not refuse perfume.” [Bukhari and Tirmidhi]
 Abu Hurayra reports that the Messenger of Allah (PBUH) said, “Anyone offered rayhan (basil perfume) should not decline it. It is light in weight and fragrant in scent.”[Muslim].
Cleanliness is an obligation in Islam. In the following Hadith, the meaning of a clean and pleasant body and soul is portrayed by Sayyiduna Anas:

“I did not touch any silk brocade nor silk softer than the palm of the Messenger of Allah (Allah bless him and give him peace). I did not smell any scent sweeter than the scent of the Messenger of Allah. I served the Messenger of Allah, may Allah bless him and grant him peace, for ten years and he never said to me, ‘Uff’ nor did he say about anything I had  done, ‘Why did you do that?’ nor about anything I had not done, ‘Why did you not do that?’“ [Bukhari and Muslim]