I would also like to improve my skills in UX/UI and product design (for those who don´t know about these terms, are related abouto my job and studies), and I want to start going to the Gym and eating more healthy.

This last thing is what has cost me the most, becausehas been the most difficult. I triedy to be disciplined with Gymget into good gym habits every year but u. Unfortunately didn´t make it :( ¶
, I have yet to make progress. :(¶
¶
Thanks for reading!

[This last thing is what has cost me the most] cost will probably make most people think about money instead of effort. "difficult" is clearer and makes the sentence flow better.

[I tried to be disciplined with Gym every year] tried implies you're giving up, and the efforts are in the past. try instead indicates a continued struggle. "disciplined with gym" comes across very awkward, instead of the intent of discipline a more concrete goal you're trying for will sound better. I changed this to good gym habits because that is the closest to discipline in my mind but 'exercise more', 'get in shape', or 'find a good gym routine' would all work here.

[but unfortunely didn´t make it] "Unfortunately" is spelled wrong. "make it" makes this feel like a pass or fail kind of thing. progress fits better because you can make a little or a lot of it instead of making it or not making it. a different clause like "It's been a struggle" or "I keep forgetting to go" would also work while also specifying what's you think is in the way.

I would also like to improve my skills in UX/UI and product design (for those who don´’t know about these terms, are related abouto my job and studies), and I want to start going to the Gym and eating more healthyier.

1. “More healthy” technically works, I wouldn’t bat an eye at it, but I can sound a bit weird in some circumstances so it might be better to use “healthier” instead

This last thing is what has cost me the most, because I tried to be disciplined with going to the Gym every year ,¶
but I unfortunately didn´’t make it :( ¶
¶
¶
Thanks for reading!

What I wWant tTo dDo bBefore the yYear eEnds

I want to learn English ato a professional level, above all.

I would also like to improve my skills in UX/UI and product design (for those who don´'t know about these terms, athey're related abouto my job and studies), and I want to start going to the Ggym and eating more healthyier.

This last thing is what has cost me the most, because I've tried to be disciplined with Gthe gym every year, but, unfortunely didn´, (still) haven't makde it. :( ¶
¶
¶
Thanks for reading!