The purpose of our lives whether holistic to the entire population of the earth, individual or by cultural groups most likely includes a component of pleasure.

This should not be applied in the hedonistic sense, personal pleasure at the expense of everything else,  but for each of us life without pleasure to some extent will be quite empty and void.

Anytime

I have run into dissenters from time to time but my own philosophy is fun, laughing, joy are always appropriate.  Actually probably even more so in dire circumstances.

I my life on earth was not intended to bring joy (both to myself and others) than what?  I can imagine no other purpose and while times of adversity are sometimes unavoidable the ability to create fun is always within your grasp.

Appropriate Behavior

I will concede that social and cultural norms do put some limitations on when and how to have fun, but these can always be overcome, albeit gently.

Crashing a sober occasion like a bull in a china shop with joyous antics clearly is not appropriate but being somber and sad exclusively is not necessary.

I told appropriate amusing anecdotes at my parents funerals, in good taste and within acceptable context of the audience.   This went over exceeding well and I received many complements.

Don’t Let Calamity Overwhelm

Laugh through your tears, you will never regret it.  My own personal mantra, sadness should be a fleeting emotion, joy and happiness forever.

Bring a little humor and fun to everything you do, I guarantee you will never regret it.