Growing older I have also found I tend to take life too seriously. I think it is important to socialise with friends or family who have a fun sense of humour, to lighten you up.
Children in particular are a great source of fun, my two small nephews are hilarious.
My husband despite being 42, also has a childish sense of humour - He thinks it is imprtant to hold on to your inner child. What is wierd is that when he laughs really hard he doesn't make a sound, his whole body just shakes even if he has tears of laughter rolling down is cheeks.
We also regularly make a point of watching comedy movies.
Maybe, look up jokes on the internet.
When things get really stressful, take a step back and look at how bizarre life can be - have you seen some of those funny looking animals out there? There are some really wierd ones.
Anyway a joke to cheer you up, the only one i can think of at the moment.........
An elderly couple were sitting up side by side together in bed.
Reaching into his bedside cupboard the husband took out a large shot-gun.
When he put the gun to his head his wife started to laugh.
Annoyed, he turned to his wife and said "I don't know what you are laughing about, your next!"