We take the sun for granted. But when we don’t get to see it for a prolonged time, a certain mental depression sets in. For some, the mind loses its positive vibrancy and hope.
In some northern and southern parts of the world, the sun is literally present for only a few hours to “not at all” during winter. Absence of the sun leads to a mental disorder called the S.A.D. [Seasonal Affective Disorder]. A psychiatrist acquaintance told me they treat this symptom by making patients spend time in artificial sunlight.
A temple is like this artificial sunlight for patients like me who do not see the sun of Selfless Love (prema) shining within. Because I do not see this sunshine, my mind becomes troubled. My mental disorders have been diagnosed as selfishness (swartham) and the temper of “me” and “mine” (ahamkaaram and mamakaaram). Spending some time in the protective sunlight of the temple treats these mental disorders through the medicine of devotion (bhakti).
The natural law is I cannot be happy when someone else is unhappy. I cannot be peaceful when someone else is suffering. My well-being is the same as, and no less or no more than, the well being of all. Impulse to seek the welfare of all comes only when I love God, be devoted to Him and act per His instructions.
Temples nourish devotion
Kanchi Paramacharya [Kamakoti]
Kanchi paramacharya says temples do us lots of good in developing devotion (bhakti).
The one cure for all human ills is the power to endure them with faith in God’s grace. Bhakti alone can give that power of endurance. Temples are the agencies for the cultivation of bhakti. 
Temples nourish gratitude
I’m grateful to you [Source]
Gratitude for help received is a cardinal virtue . The opposite is also true. Lack of gratitude is a sin of the highest order. Even a dog has the virtue of gratitude and shows it sometimes even at the cost of its own life.
In a temple, I show gratitude to God for all the things He has gifted me with. Every breath I take in is His Gift. The sight of vision, the ability to hear, smell, touch and imagine – all these are His gifts. And the innumerable things nature offers for my enjoyment and pleasure – these are all His gifts only. Once a medical student told me in wide-eyed awe that so many things can go wrong in our body but the wonder is they don’t. Is health not a gift from God? The gifts I have from God are truly infinite. The most enchanting of them is the gift of Love (prema)
In a temple, I show gratitude to God for all the things He has gifted me with by making offerings. To be sure, God does not need or seek my offerings. But I do this so I can learn the virtue of gratitude and become better at it.
Once a friend asked me would it not be better to divert the offerings we make at the temple to serve the poor and the needy? To be sure, serving the needy is paramount. But one doesn’t need to divert the temple offerings for this purpose because they are not mutually exclusive. Both serve the same purpose. Developing sincere gratitude and love for God equips me to serve others in the truest sense of service. Service becomes a wholesome part of my life then.I make offerings at the temple – and should do so – for the welfare of all.
Temples nourish community goodness and social service
Even a crow shares the grains of rice it comes across with other crows, in gratitude for the food it has received. But do I share what I have with others? Do I share my wealth, time and skills with the needy?
Temple prayers are for the welfare of all beings in all the worlds. Temples serve the needs of the community, especially the hungry. They provide free food for all.
Free sumptuous food served lovingly at Shirdi 
Here is an example of ten temples providing free food on a gigantic scale daily. The Golden Temple, Amritsar provides free food to upto 100,ooo people a day [ Video]. The Thirumala Balaji Temple provides free food to thousands of people daily [Video]
Temples nourish character and promote proximity to divinity
The very word, “mandir” (temple), the very sight of it, sends positive vibrations and energizes the body and mind. It generates divine feelings from within. I’m at my best behavior inside a temple. I speak softly and do not lie. I show respect to others. I try to be peaceful, thinking of God and good thoughts. I exhibit human behavior more inside the temple than outside it.
I pray with my eyes closed so I can be close to the indweller within me. Temples enlighten and enliven my living.
Temples nourish art and culture
Every temple I go to is an art museum . No less. What marvelous, exalted and elevating beauty I see in the bas reliefs, in the architectural design of pillars and mandapams, in the choice of colors, in the spatial design, in the sculptures and in the paintings in temples!
Music concert at a temple. Temples are storehouse of culture 
Temples provide a uniquely comforting atmosphere for music concerts, dance performances and plays – all promoting devotional themes. Both the performers and the audience experience the performances inside a temple in a way that is exhilaratingly different from their experience outside the temples.
Science salutes temples but temples are beyond science
The sun passes through all doors of Anathapadmanabhaswamy temple at equinox. An engineering marvel 
Today, intelligence is noisier than intuition and science is louder than scriptures. If science says something, then it must be true, is readily accepted and quoted. When science discovers and confirms the truth mentioned in scriptures, it is a “hooray!” moment for the wisdom of our ancestors !
Temples are no exception to this bias of ours. Read here for scientific explanation of some of the benefits of visiting a temple and what we gain from the sights and sounds in a temple.
But temples are beyond science. Scientific explanations miss the most important benefit of visiting a temple. Temples are much more than brick and mortar or sight and sound. Temples are a doorway to divine experience itself. Entering a temple gives a divine feeling. Standing before the altar, closing the eyes and thinking of God makes time stand still – even if it be for a moment.
Exiting a temple, I resolve to overcome negative thoughts and bear all ills with faith in God’s Grace. My mind becomes stronger and more resilient. I become calmer and recharged with a shot of confidence to march on with life’s myriad challenges and opportunities.
Do all temples provide these benefits?
Potentially all do, but in reality only some do. Today many temples have become cash spinning machines only. In the name of religion and spirituality, their practices have become heavily commercial, especially in USA. Time-tested guidelines from scriptures have taken a back seat for the sake of money. Divine vibrations are not easily available at these temples. One has to dig really deep to commune with the peace within. These temples do not facilitate the development of bhakti and are misleading the gullible.
Temple visits guide me to the “temple within”
One of the great things temples do is they direct me to the temple within – the temple I’m always carrying with me. The more love I develop for God, the more gratitude I feel for Him and the more I genuinely care for the welfare of others over my own – all these resulting from my temple visits – the easier it is for me to see God as the Selfless Love (prema) within me.
The body is a temple. The indweller is verily God.
Deho davalaya prokto deha jeevah sanatanah
To love and embrace the Love within is the greatest good temple visits do. This can happen without going to the temple also. But visiting a temple diligently, lovingly and regularly makes it easier.