The England back row says head coach Heyneke Meyer demanded higher levels of fitness in the squad and that has helped them win their opening three games of the Guinness Premiership campaign.
Croft said: We are definitely fitter as a squad. We had a very hard pre-season after a lot of cardiovascular sessions each week.
The good thing was the boys wanted to do it. It was the boys chomping at the bit to get into these sessions and improve themselves.
The boys have said throughout the pre-season games and the first weeks of the Guinness Premiership that we feel fitter as a squad.
It showed against Gloucester that we fought to the 85th or 90th minute to seal that win, we scored late on at Worcester, and its obviously paid off.
Tigers are now preparing for a Welford Road double header, against London Wasps on Friday and then Northampton Saints next Wednesday. Tickets are available now from the Tigers ticket office on 08701 28 34 30, book online or call into the ticket office.
Croft added: Its been a good start to the season in terms of results but there are a lot of things that we didnt get quite right against London Irish and a few things that went wrong against Gloucester and Worcester.
We are not where we should be at the moment, but we are working hard in training to tighten those bolts up. Hopefully we can soon be firing on all cylinders.