How to get motivation to exercise

Hi everyone,

I have had severe depression for 3 years, I used to love sports and exercised regularly.
Now I struggle to get out of bed and I sit at home all day..
I have a small dog that never gets walks, because I find this an almost impossible task, to take care of him and/or myself.
I'm a teenager by the way, so does anyone have some tips or advice that would be useful to start trying to build regular walking habits and keep it up?

It probably sounds easy to say just get up and do it, but if we could do that I don't think depression would be a problem at all.

Thanks ,
Feather11