Eva, that is a very limited and cosmopolitan view of karma. It's not really like that at all. 

Karma is like a rucksack that you have constantly on your back. Bad thoughts have a weight of 50 grams, bad words 100 grams, bad deeds 1 kg. The same is with good thoughts that deminish the weight of your rucksack about 50 grams,  good words 100 grams, but good deeds reduce the weight of your rucksack   in a whole kilo.

Karma is much more than simple cause and effect and is such a big subject that to discuss it here would probably just collapse into an unrelated religious debate having little to do with karma. Westerners like to simplify things a great deal, but when you water down the concept of karma it can seem a bit silly, which is a sad thing to do to such a powerful and important concept.   

The faith in different things created by humans. "Karma" is one of them. I believe that everyone can "write his story of the life". :)