Why does restlessness break focus in meditation despite comfortable chair?

Mujhe dhyan lagate samay bahut restlessness hoti hai, aur mera focus baar baar toot jaata hai. Log kehte hain ki aaramdayak chair zaroori hai. My name is Suhail, born on 9th August 1994. Time: 8:05 AM. Location: Surat. Kya physical discomfort mere dhyan mein itni badi rukawat hai, ya main zameen par baith kar bhi safalta paa sakta hoon?