The following is an amazing article detailing correct sitting posture – perfect for those working at home during Coronavirus.
Basic premise is to have pelvis positioned correctly as a good foundation (in the words of the author – “have your tail out”). Think of how children at a very young age naturally stand. It should be relaxed and will also be comfortable. It is not a forced position. You should not feel tension when sitting correctly.
This helps have correct spine position and helps prevent back problems.