New Delhi: Staying inside a bio-bubble "isn't easy" but Indian football captain Sunil Chhetri, nevertheless, is bracing up for the upcoming Indian Super League (ISL) in earnest, doing all it takes for a successful campaign with his franchise Bengaluru FC.

From doing double training sessions and reading books, to watching renowned broadcaster and historian Sir David Attenborough's A Life On Our Planet, the 36-year-old has been one busy man through the last three weeks of the team's quarantine in Goa.

"This is our third week inside the bio-bubble and I must confess it isn't easy but, of course, needed," Chhetri said in a video he posted on his Twitter handle.

"We are doing double time session and we are trying our best as a team to be as fit as possible before the tournament starts."

The ISL kicks off in the coastal state on November 20 with a game between ATK Mohun Bagan and Kerala Blasters.

The seventh edition of the tournament will be held in three venues of Goa and not across the country owing to the COVID-19 pandemic.

"It's just 10 days left and I am pretty sure all of you are waiting for the ISL as I am and the whole team is.

"Among all this, I am trying my best to find some time for myself I just finished reading a lovely book -- The Body by Bill Bryson -- and I highly recommend this," the ace striker said holding the book.

"Also me and wife we just finished Sir David Attenborough's 'A Life On Our Planet' and it's outstanding. We spend so much time on social media and watching television, I recommend you guys to spend one and half hours watching Sir David Attenborough's career.

"You watch, I won't spill the beans, it's an amazing series, especially the young ones. Please indulge in it and I am pretty sure you will find your time is worth. And I must confess or admit that neither Bill Bryson nor Sir David has paid me anything to do this."

Chhetri, currently the world's second highest goal-scorer among active footballers -- only Portuguese Cristiano Ronaldo is ahead of him -- will spearhead former champions Bengaluru FC's challenge this season.

Bengaluru FC, known for a professional setup since its arrival on the big stage not too long ago, won the tournament in 2018.

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