Fast bowler Mitchell Johnson was "really happy" with his performance in Australia's warm-up match against Kent last week after struggling to focus following Phillip Hughes' death in November.
Johnson, who was devastating with the ball in Australia's 5-0 Ashes triumph over England in 2013-14, was less effective in the most recent Australian summer in the aftermath of Hughes being struck in the neck by a ball during a Sheffield Shield match.
Hughes never recovered, eventually passing away in a Sydney hospital, and Johnson conceded on Monday that his on-field performance suffered as a result.
The 33-year-old paceman had the fourth-best bowling average in Australia's 2-0 Test series win over India and the sixth-best as his country won the Cricket World Cup on home soil.
"I'm not someone who makes excuses, but we went through a bit of a time just before that with Phillip Hughes and that was something very difficult, and it was really hard to sort of deal with it at times," Johnson told the ABC.
"We were definitely underprepared [for India] at that time and my pace was definitely off.
"I probably wasn't fully right, fully mentally right, there at that time, so I just got through."
After taking 4-56 and 1-29 in Australia's opening match of their tour of England, Johnson feels he is back to his best.
"I was really happy with how I bowled against Kent," he said.
"I felt really good, good rhythm, good pace, something I was really excited about here was bowling with those Duke balls.
"Since I got here, I just feel it in the air, there's something I don't know, it's just really, really exciting at the moment - and my job is to bowl fast."
During the most recent Ashes series, Johnson was the leading wicket-taker with 37 at an average of 13.97 and the left-armer hinted his reputation may be worrying the more inexperienced members of England's squad like Adam Lyth, Jos Buttler and Moeen Ali.
"They've got a few new players in their team, so they haven't seen me yet or played against me, so I'm hoping that's going to play in our favour a little bit," Johnson said.
The first Test of the Ashes will start in Cardiff on July 8, with Australia completing their preparations with a tour match against Essex, starting Wednesday.