"I live well."
"Jól lakni", or, actually, "jóllakni", means to eat until you are not hungry anymore. :) That is just a bonus information. :)
Other than that, "lakni" is probably more closely related to the location, and not the quality, of your living arrangements. You can say "jól lakom" if you want but it does not make too much sense. If you want to say that you have a nice home, you would rather say "jó lakásom van" - I have a nice/good flat/apartment".
Besides, to live well can mean that you eat at a restaurant and go to theater everyday. "Lakni" is just about your place of residence.