Many candidates struggle to speak for 2 minutes because they answer the first two or three points on the task card too quickly. They only give a detailed answer for the final point.
Look again at my sample answer in " IELTS Speaking Part 2: indoor game answer " . Notice how I answer each point on the topic card in detail. Instead of answering the first point with just one sentence (e.g. "Im going to talk about chess"), I added three more sentences describing the game. I did the same for the questions about where and who.
The last point on the task card usually asks for your opinion (why?), and its easy to say more about this. However, if you want to fill the 2 minutes, I suggest that you practise giving longer, more detailed answers to the first three points on the task card.