A devotee, as explained in religion, is a person who has some goal in mind, wants to achieve something, is seeking to realize the ultimate reality. To realize his goal he has to follow the advise of some holy person, a guide, somebody who has already realized that state.
In Hindu tradition, the devotee is called Shishya, and that holy advisor is called Guru. It is a holy relationship of Guru and Shishya.
One of the wonderful example of Guru Shashya relationship is saint Eknath and his Guru Janardhan Swami, you can read more about this in my article of Eknath which was published on 17 Oct 2017. It is similar to the relationship between Jesus and his disciples.
However, there is a misconception among people that the devotees or spiritual people are very serious, they follow a strict discipline, they cannot laugh loud, they are beyond all these traits. But it is not true. Infact quite the opposite is true.
A devotee is not very serious, he is very cheerful. Why should he be serious, why should he worry? He is not bound by the bonds of the world. He is free. He has got the guidance of his master, his Guru. He is on his way to realize the almighty.
In Hindu tradition, the devotee, infact all man are Sat-Chitta-Ananda.
Sat -> Existence, Truth
Chitta -> Consciousness
Ananda -> Bliss.
It means everthing that exists(Sat), when it is experienced in the divine consciousness((Chitta), and in that state he experiences ultimate peace and ecstacy((Ananda).
All man indeed are Sat-Chitta-Ananda. They experience the truth. In that union they experience the divine ecstacy. Is there any reason for a person to be serious, morose or despondant ?
Infact a person who has made even little spiritual progress, is so happy, cheerful that people around him love to talk to him, speak to him, be in his holy company, because he will never speak bad about anything, he is unselfish and truthful person.
There is a beautiful incident about Swami Vivekananda, which I would like to quote. When Swamiji was in America, in one of the gathering, he was enjoying, laughing and joking with people in a friendly manner. One of the lady went to Swami Vivekananda and said, you are a monk, such behaviour is not suitable for you. To which the great monk explained that people who believe in God are never in any fear and have faith in God, so they are always cheerful and happy.