Try make yourself laugh first! Stay natural, don't be the funny one if you are not... but try to be as funny as you can.
I mean. Not everyone has it naturally, but they have other qualities.
When you like your own jokes, then at least you like it and you stay with yourself. Maybe you have some secret funny talent hidden inside?!
Just stay realistic. Not everyone has 'it.' Don't try to become funny trying to get admiration or something... then it is better to learn your real talents and use them to get better and the admiration will follow. Everyone has some talents at least.
Good luck!