"because they fit my interests and talents, have a lot of benefits, and have good career outlooks." This would be very good except that in this context "have a lot of" sounds too informal--like spoken English rather than written English. I would suggest "many benefits" or "numerous benefits." Although it is good English and flows smoothly, I would probably leave out "Although there are many other jobs in the world," because it adds little to the meaning. "I want to become an advertisement designer, application developer, and an interior designer for my future career" is wrong, because it sounds as if you want to do all three. You need to use "or" instead of "and." You could say "I am considering three possible careers: to be an advertisement designer, ..." Or, "I am considering careers in I find the list puzzling because "advertisement designer" and "interior designer" sound like visual design careers, while "application developer" sounds like a technical career, requiring a completely different skill set.