I'll do it
Si no lo hago yo lo tendrá que hacer otro.
If I don't do it, someone else will have to.
Deja, lo hago yo, tú descansa.
Don't worry, I'll do it; you get some rest.
— Mujeres al borde de un ataque de nervios (1988)
I'll do it myself.
Watch how I do it.
You do it or I do it.