Let me tell you a story from Lord Buddha's time....
One day a maid who was a follower of Lord Buddha went early in the morning to the nearby river to bring water.
She saw a sage in the river taking an early bath, knowing the temperature of the water in the morning she asked him a question.
Dear sage what are you doing in this cold water, it is very cold in this part of the day?
the sage replied, I am washing away my sins. When i take cold baths it brings me closer to salvation.
The maid was surprised by the answer and said,
Dear sage if cold water brings you closer to the path what about the fish in the water?
Then she went on to describe how mind matters to the path not the body.
This is what you should take from this story...
Lord Buddha clearly said "Mind is the thing that comes first,that it is on top of the order".
Lord Buddha also said "thoughts are Karma" ("Chethanahan Bhikkave kamman wadami")
It is the mind that matters not the body...
Let me convince you with some stories from the history of the Great Arahats,
One day a determent monk started to do the walking meditation around the "Bodhi tree" of a monastery. The monk was determined to keep going no matter what. After some time he felt that his legs hold no more power to carry him and he fell down, but he did not stop. He started to keep going on his knees. Then his knees gave up on him after some time. He was bleeding and fell down on the sand. Later on he was directly instructed by Lord Buddha to take things slow, Not too hard and not too soft.
So this is how taking things too hard ended up. Now lets see how taking things too soft ended up...
In the early age of Buddhism monks used a wooden pillow to rest their heads when sleeping. But this was later on replaced by the kind of pillows we use today.
And it can be found in many dialogs among Monks and Arahats (In text) that this replacement which is seemingly good actually reduced the potential of the monks. It was considered a bad choice because the replacement actually represented the love for the well being of the body.
So have people or monks meditated without any regard to their bodies?
Here's the answer...
Once there was a monk called "Ven. Chakku pala". while he was at the peak of his practice he started having troubles with his eyes. The doctor gave a medicine which needed to be dropped in to the eyes while the patient is lying on a bed. But he could not agree to that because the practice style he was doing needed him in only to poses (sitting or standing). So all along he was either standing or sitting,skipping the sleeping. He chose his Nirvana above his eyes and kept going. In the very day he turned blind he reached Nirvana.
Do not have many concerns. Try to relax and not to worry about the minor details. If you have pains while meditating do some vipassana meditation and focus on the impermanence of that pain and keep going on. It is essential that you give up the love for your own body and to do that you need to learn and realize just like all other things your body is temporary too.
Be strong and keep it up,
May triple gems bless you!