The former Cleveland Browns running back was traded to the AFC South side last month, rushing for 95 yards and scoring two touchdowns in his first two games with the team.
The 22-year-old told the team's website: "[I'm] much [more] comfortable. At first, it was kind of difficult. I really had only two days to practise before I got on the field my first week.
"I had a full week last week. It's only really going on my second week now. It's much easier. There have been a couple of runs I should have broken. It's going to hit. It's going to come. I see the runs in front of me.
"I know the 100-yard games are going to come. I do say 'games', because there's going to be more than one. When they do come, it's going to keep coming. It's almost back to being a rookie again."
The Colts play the Seattle Seahawks this Sunday.