Picture the scenario
A new member comes to class and finds sitting on the floor extremely uncomfortable (in fact something that many new class members find tricky at first), so to help make the activity more accessible the teacher offers a yoga block to sit on, and an alternate way to sit. That person happens to notice that on that particular day nobody else is sitting on a block, they then feel self conscious, and like an idiot because no one else is sat on a block and decides to never come back to class again because they think everyone is looking at them and laughing at them for needing a block.
No one is laughing - no one is looking at them - most of them have probably sat on that block at some time. The teacher is not pointedly singling them out to make them feel stupid but is trying to make the class as accessible as possible, if they leave them in pain does that make the class any better - the pain itself will probably put them off from returning!
Now picture this scenario
That new class member takes the block and the advice, keeps attending class and improving and after a little while has the huge pride and satisfaction of being able to sit on the floor comfortably like everyone else - the whole class and teacher congratulates them! WIN WIN WIN
Class teachers/activity leaders have been taught how to treat each member as an individual and to make the activity as accessible to everyone as possible. They put time and money into making sure there are props and ways for different body types to access the class/activity. All the members in the class/group are excited to have a new member join and keep that activity going and progressing.
YOU ARE NOT THE ELEPHANT IN THE ROOM - your class teacher/activity leader is trying to give you the best experience possible. Don't give up on it you will always be a valued member of that group!!!!