What or what Who Motivates You? ...

1) In your work or studies.

My dad in particular motivates me in my studies. He's the person who encourages me to pursue one's my studies. He thinks that knowledge is really important.

2) To improve your English

My dad has always incited me to improve my English. He speaks English quite well and he has also studied also in England. Choosing languages as  a degree now I'm has really motivated me to improve my English.

3) To improve other skills, e.g. sport, music, other activities (give examples)

My parents always motivated me to improve other skills, but when I was a child I didn't like any skill in particular.
Now I really love sport and I've been practicing kick-boxing for 9 years. A man who motivates me in this sport is my trainer. I'm also  trying also to learn to play guitar and for this I have to thank my boyfriend who loves music.
I also like to take photographs. Photography and particularly take portraits is my greatest passion. My parents motivated me when they bought to me my first camera but always all the people everyone who loves my photographs incite me to do better.

I prefer "urge" to "incite"

What or what who motivates you...

1) In your work or studies.

My dad in particular motivates me in studies to study. He's the person who encourages me to pursue one's my studies.

This second sentence is slightly redundant and one's is definitely out of place. Maybe you could use a noun to reflect the qualification you are studying for instead. For example "… my degree.".

He thinks that knowledge is really important.

2) To improve your English

My dad has always incited encouraged me to improve my English. He speaks English quite well and he has also studied also in England. Choosing languages as degree now I'm really motivate to improve my English.
This may be better "Having chosen to study for a degree in languages, I'm now really motivated to improve my English".
3) To improve other skills, e.g. sport, music, other activities (give examples)

My parents always motivated me to improve other skills, but when I was a child I didn't like any skill in particular.
Now I really love sport and I've been practice doing kick-boxing for 9 nine years. A man who motivates me in this sport is my trainer. I'm also trying also to learn to play guitar and for this I have to thank my boyfriend who loves music.
I also like to take photographs. Photography and particulary take portraits photography is my greatest passion. My parents motivate inspired me when they bought to me my first camera but always all the people who love my photographs incite motivate me to do better.

"What or WHO motivates you" is the correct title. I've made a mistake.