If your colleague asks you to go down for a chai or join them for an outing to a nearby place in the middle of work hours, do it! Once or twice, it is fine but refusing to go with them every time will eventually make you the boring one. No one will ask you again and you can also feel unwelcomed after a while.
Be yourself
Don’t fake a personality you do not have because eventually your true side will come out and people do not like such people like you don’t. you’re more likely to be labelled with a split personality disorder if anything. Being fake is not a good look and most people can see right through this.