Doing sport

It has been a long time since I did any sport.
Last year I loved to go to the gym every day. I was going to aerobics classes, to be more accurate.
At first it took me quite some time to be a person who goes constantly [regularly] to the gym. However, as soon as I became used to it, I was going to the gym every single day. 

Currently doing sport is very difficult for me as I haven't got any free time. My time is completely taken with [I am busy] working and studying English. But that is going to end!

I've downloaded a workout exercise video and I'll try starting with that. The first step is the biggest [hardest], but once you've taken the first step, the next is easier!

Comments in blue, corrections in green

Doing sports

It has been a long time since I don't do anything of sports activity.
Last year I loved to go to the gim gym every day.
I was going to aerobic classes to be more accurate.
At first it took me quite of time to be a constant person become a regular, one who goes to the gym usually.

(You could also say " At first it took me quite of time to get used to them, and to go to the gym regularly.")
But as soon as I got used to it ("it" to signify the routine or "them" to signify aerobic classes) I was going to the gym every single day.
Currently doing any sport is very difficult for me. I haven't got any time, my free time is completely bussy utilised for working and studying English ( "utilised" is a better word to use here than "busy"). But that is going to end!
I've downloaded a workout exercise video and I'll try to start with it. The first step is the biggest! But once you have taken the first step the next is easier!

(Good essay!)