The singer - who rejoined the band last year, 15 years after he first walked out on the group- famously suffers from crippling stage fright but has taken up some calming hobbies to help with his nerves ahead of the stadium shows.
A source close to the star told the Daily Mirror newspaper: "Rob suffers from crippling anxiety and has been worried about the lads` forthcoming concerts. A pal suggested Bikram yoga to refocus his pent up energy and handle stress more effectively."
Robbie has reportedly been attending Bikram yoga sessions for the last three months, which see him strike a number of meditative poses in a room heated to 40 degrees centigrade.
The source added: "After a couple of sessions he was hooked - and sweating like a wildebeest. While the others have stuck to the gym or pool, Robbie`s been using meditation and yoga to help his stage fright and to keep sane on tour."
The `Rock DJ` hitmaker - who is joined in the group by Howard Donald, Gary Barlow, Mark Owen and Jason Orange - previously admitted he started to get stage fright after touring for excessive amounts of time as a solo artist.
He said: "I`m not the kind of person who can do nine months. I can do two months solid, not a problem. But nine months - I`m not built for it. I go loopy.
"But mentally, all I`m projecting is very positive, all I can see is it being healthy and happy and an amazing show."
Mark has also admitted he recently suffered a bout of stage fright ahead of the shows, in support of the band`s `Progress` album.
He said: "A few weeks ago I had a pre-tour panic, a bit of a meltdown, which I went through for a couple of days. I wasn`t getting much sleep, but I came through the other end and I`ve been all right since."
The group will play 36 stadium shows across Europe, ending on July 29 in Germany.