Learning (<--Esto suena mejor en un título) to play an instrument

One of the things skills (<--Es mejor que no se usa la palabra "thing" cuando se escribe. En inglés, "thing" es demasiado impreciso.) that I would like to learn in my life is to play a musical instrument. I think you need that, to be able to play, because you one needs a level of concentration and skill. I do not want to be a big star; I just want to learn, because I think learning new things skills is good for mental health, and learning to play an instrument is something I would like to do.

What instrument would I like to learn to play? Definitely the piano or violin, because they are too very (<--En esta situación específica, sólo utilizamos "too" por el negativo y "very" por el positivo.) relaxing for me.

Excelente redacción, Arizai. Si tengas preguntas, díme por favor =)

Learn to play an instrument

One of the things that I would like to learn in my life is to play a musical instrument. I think to be able to play you need a certain level of concentration and skill. I do not want to be a big star, I just want to learn because I think learning new things is good for mental health and learning to play an instrument is something I would like to do.
What instrument would I like to learn to play?
Definitely piano or violin because they are so relaxing for me.

One of the things that I would like to learn in my life is to play a musical instrument. I think it would be good for everyone you need to be able to play, because you need a level of concentration and skill. I do not want to be a big star, I just want to learn ti's new skill because I think learning new things is good for mental health and learning to play an instrument is something I would like to do.
What instrument would I like to learn to play?
Definitely, piano or violin because they are too relaxing for me.

You did a really good job!!  I just made the te text sound more natural, you can check out my profile, I specialise in vocabulary and naturalisation of speach, I really think I can help you in this aspect :3