I want to promote cheerfulness; an approach to life simply defined as being happy, often under difficult circumstances. The cheerful person is capable of recognising the gravity of a situation but smiling nevertheless. In any ranking of virtues, cheerfulness comes below such things as faith, hope and love. Nevertheless, for all its modest ranking it strikes me as being one of those qualities that makes the world a better place.

Now I am aware that while some people are temperamentally cheerful, others are not. Some people can wear a happy little smile while they're waiting for root canal treatment; others struggle to avoid being grumpy on a cold, dark and rainy day. Indeed for some people not only is the glass of life half full, but it isn't a very good vintage and it has cost them far too much. There are also issues of circumstance: it's surely easier to be cheerful if you are young, healthy and have a good job than if you are older, frail and struggling financially. Mind you, I have known many in the first category who were miserable and others in the second who were heroically cheerful.

Cheerfulness may be a virtue but there is a widespread suspicion about it because modern culture automatically assumes cheerfulness to be shallow. Unfortunately it's not hard to find a parallel perspective within Christianity; a view of life that considers that any deep and genuine faith must be gloomy and that any display of cheerfulness reveals a lamentable spiritual shallowness. I think that cheerfulness is an expression of joy and as such is commanded of all followers of Christ: 'Rejoice in the Lord always. I will say it again: rejoice!' (Philippians 4:4).

Let me suggest that cheerfulness is vital in three areas of life.

First, cheerfulness is good for us spiritually. Cheerfulness – closely related to contentment – makes us inclined to show love to others. It also boosts our spiritual immune system and makes us less susceptible to temptations such as negativity, bitterness and anger. In the gloomy secular culture that we live in, cheerfulness is also an extraordinarily powerful, refreshing tonic.

Second, cheerfulness is good for us socially. 'Laugh and the world laughs with you; cry and you cry alone,' goes the saying and, unfortunately, it is true. Cheerful people make friends and maintain good friendships. Cheerfulness reduces tension and minimises the possibility of quarrels – it's hard to pick a quarrel with a cheerful person. Indeed there is something wonderfully contagious about cheerfulness: cheerful people can trigger a chain reaction in which other people are encouraged to be positive and cheerful.

Third, cheerfulness is good for us medically. Proverbs 17:22 says that 'a cheerful heart is good medicine . . .' and doctors would universally agree. After all, cheerfulness is not just the opposite of gloom but also of stress. As any nurse or doctor will tell you, it's the cheerful patients who get better quicker. Cheerful people not only live longer, they live better.

So how do we gain cheerfulness? The first thing to point out is that there are things that corrode cheerfulness and which, if you seek to be cheerful, are probably to be avoided. So I'm inclined to say that such things as graphic murder novels, songs by depressives and films in which all the cast die should only be taken in small doses or avoided altogether. Nevertheless, in seeking to avoid depressing things there is a problem: followers of Christ are meant to do good in the world and to engage with evil. And, of necessity, combating evil requires that we are in contact with it. It is hard to be cheerful when you are dealing with trafficked people and individuals who are painfully and terminally ill. Yet some of us must work in these situations and bring hope into them. After all, to be cheerful is to be positive in the midst of negatives.

Some things boost cheerfulness: taking exercise, going out for walks in the countryside, mixing with children, enjoying laughter and love, and meeting with family and friends. Yet I struggle with how you find lasting cheerfulness without some sort of faith. After all, to be truly and deeply cheerful is to be able to say to yourself, 'Despite it all, I know that ultimately my story has a happy ending.'

Nevertheless, even Christians can struggle to be cheerful; this is a tough world and there are some dark shadows in many places and many hearts. I think for the Christian, the secret of cheerfulness is to continuously remind yourself of ultimate realities. Beyond whatever pains and problems we face lie the eternal and unshakeable realities of the love, peace, presence and power of God towards us in Jesus. Read and ponder what Paul says in Romans 8:31–39 and note particularly verse 35: 'Who shall separate us from the love of Christ? Shall trouble or hardship or persecution or famine or nakedness or danger or sword?'

There's a story about the reformer Martin Luther, a man prone to depression and discouragement. He was sitting in his study deep in gloom when his wife Katharine came in dressed in mourning clothes of black. 'Who died?' asked Luther in puzzlement. 'It seems,' his wife replied, 'that God must have died.' It was wisely said. Let's remember all God has done for us, all he is doing and all that he has promised that he will do. And, with that in mind, let's be cheerful!

(Scripture quotes are taken from the niv)