When you have no choice but to sit, try switching the slouch  for a straighter spine, and when you don't have  to be bound to your seat, aim to move around much more, perhaps by setting a reminder to yourself to get up every half hour.
Ja tev nav citas izvēles, kā vien sēdēt, pamēģini iztaisnot muguru un tad, kad neesi piesiets krēslam, centies kustēties daudz vairāk, piemēram, uzliekot sev atgādinājumu piecelties ik pa pusstundai.