"It (captaincy) puts a bit more pressure on you to play well but I see that as a good thing," Farrell told BBC Radio 5 live.
"The first thing with that responsibility is standing up and talking in front of the team, telling other people what to do. The more you end up speaking the more you've got to do it and the more you've got to front up.
"I've always been comfortable speaking, especially on the field. Probably not as much off the field."
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Farrell believes he has the leadership qualities to step into Hartley's shoes as Eddie Jones' side looks to snap a run of poor recent performances.
England were beaten by Scotland, France and Ireland in consecutive fixtures to finish a disappointing fifth in the Six Nations tournament earlier this year.
"I'm not trying to be anyone else. You can either let the pressure get to you or let it help make you better. I see it as something to get excited about rather than try and worry about," Farrell added.
Prior to the South Africa tour, which begins with the first test on June 9, Farrell will look to help his club Saracens beat defending champions Exeter in the Premiership final at Twickenham on Saturday.
(Reporting by Shrivathsa Sridhar in Bengaluru; Editing by John O'Brien)
