Maxwell, 27, suffered damage to his kidneys in a hard hit from West Coast's Andrew Embley in the Magpies' NAB Cup semi-final win at Patersons Stadium three weeks ago.
While he will sit out of the Pies' season opener against Port Adelaide at Etihad Stadium on Saturday, he has his eye on their round two clash with North Melbourne in seven days' time.
"I lost probably three or four kilos but I've put it all back on now in training and I'm looking forward to getting my fitness back up now," he told Triple M radio on Saturday ahead of the Port clash.
"The [insides] are not too bad. It's not ideal but I'll start to do some training this week, which is good.
"I took the doctor's advice and spent a couple of weeks in bed, and one positive out of it was that I spent two weeks with my daughter, which was good because she's eight weeks old and at least she knows who I am."
Earlier, Maxwell told 3AW radio he had the clash with the Roos in his sights.
If he fails to play next weekend, he will certainly want to be included in the Pies' round three Friday night blockbuster against Carlton, where the club will unfurl its 2010 premiership flag.
Maxwell, who missed the Pies' NAB Cup triumph over Essendon two weeks ago, said he had been stunned at how focused his teammates were when they returned from their holidays last year.
"After the season, we were something like the youngest team in 40 years to win a premiership," he said.
"I was fearful coming back into the start of pre-season. I thought we were going to be slow starters in the pre-season.
"When we started mid-November in Arizona, I was really fearful of that fact, that we would have celebrated a bit too much and guys wouldn't quite be right.
"But I was blown away when they came back with just how they switched straight on to the job at hand in 2011.
"Given it was such a young team, I thought they might have had a lapse but we couldn't have asked for any more at this stage."
He said he invited the Pies' senior players - those aged 24 and older -for dinner two weeks before the start of pre-season to talk about not letting their form slip away in a premiership hangover.
"I just said to them, 'We're such a young group with the guys 23 and under, they can improve five, 10, 20, 30 per cent over a pre-season, because that's just what happens," he said.
"I said to the senior guys, 'We need to find our extra one or two per cent. We can't just sit still. We've got to find one or two per cent individually and then that will drive the group forward'."
He said the loss of defender Nathan Brown to a season-ending knee injury during the pre-season was the only negative to come from the summer.
Maxwell said coach Mick Malthouse was the right man to lead the side this year having been involved in sides (Richmond as a player and West Coast as a coach) that slipped after winning flags.
"Given it's his last season of AFL coaching - that's what some people think - he's the right person to be taking us forward because it's his last year and he wants success."
