First, adults don't always benefit from prolonged practice the way kids do. You might advance just as quickly with 2-3 much shorter daily sessions, totalling 45 min to an hour.
People vary a lot esp as adults, it's just something to try.
Often I find keyboarders using a lot more force than they ought to. Chris Hamilton's comments were important. To a musician this is always scary, it feels like you've had a minor stroke or something. You feel the need to fix it instantly so you end up forcing. If you've done no damage you'll recover in a few days.