Hey Office Chair Holdouts, Get Yourself a Seat Cushion at the Very Least

Purple made a name for itself with its mattress. It repurposed that same technology, the Purple Grid, for when you're sitting up, too. The grid construction is, as the brand claims, "instantly soft where you want it" and "firm where you need it." The Royal seat cushion is the best of the bunch for its universal size and ample height. And because of the grid, heat is able to travel away from your body so you don't overheat.  The cushion includes a machine-washable cover with a handle so you can bring it on the go.

The thing with contoured seat cushions is that they aren't one-size-fits all. While Tempur-Pedic's is the most expensive one on this list, if this one fits you and your chair, then it's a real winner. Reviewers found that the cushion is supportive and firm, and it didn't get too hot after prolonged sitting. The contouring works especially well for relieving pressure off your tailbone and hips, which contribute to that achey feeling you get after sitting on a hard-seated chair too long. 

This cushion is less-so about providing rear support than it is about promoting active sitting. Even the most expensive office chairs inherently encourages us to to stay immobile. By adding a wobble cushion, you'll be forced to stabilize your core to stay put — hence "active" sitting.  The cushion is inflatable, and reviewers noted that that the rubber material doesn't make a squeaky noise. It also doubles as an independent exercise tool for strength and balance exercises.