How do i get all my skills full without doing all the work? Is there a cheat for this?

If there is a cheat, I'd like to know it, too. But, of the six skills, only Charisma and Body are time-consuming and take forever. I don't know which expansion pack they come with, but there are some other items (besides mirrors and the exercise machine) that can be used to improve Charisma and Body skills while also building the Fun stat, but I'm not sure how well they work.

Cooking and Mechanical take a while, but these can be done for a couple of hours (assuming their stats are high enough to take it for that long) each day, and eventually they'll be filled. There are also some items (again, I don't know which expansion packs) that will bulid the skills that may also have beneficial side-effects, but I haven't tried those yet.

Logic and Creativity are easiest to build, since they also improve the Fun stat as well. Have your Sims play the piano (my preference) or the guitar (not so much) or paint (might take longer, but you get a little money out of it eventually) to build up Creativity. If your Sim's Fun stat is really low, and they're willing to play the piano, it won't take very long to build the Creativity skill at all, because they'll keep playing the piano even beyond the fulfillment of the Fun stat. For Logic, the checkerboard and the chess set are the best, and if you can engage one other Sim to play, then you'll be able to improve not just the Logic skill and Fun stat, but also the Social stat. Because your Sim is sitting for the board game, the Comfort stat will also rise, depending upon the kind of chair you use for this.

If you do find a cheat to build skills quickly, please share it!

Idunno if this will help but, this place has replicas of the skilling objects that don't require the sims to be in a good mood to use them. That kinda makes it easier for them to get skills faster. It helps me anyway