The West London outfit are due to face the Singha All-Stars in their opening pre-season clash following a number of intense training sessions.
"At this moment the players are tired but we are not worried because we understand the process and in the first week this is normal," Mourinho told the club's official website.
"The players know because they have some experience that in one more week they will start the recovery from this period of accumulation of fatigue, and they will feel much more comfortable.
"After a week I am still the happy one because my boys have been fantastic because nobody stops, nobody wants to have rest and we are working very, very hard."
Chelsea's opening Premier League fixture in the 2013-14 campaign is against top flight new boys Hull City.