With a laptop it's important to raise it up on a pile of books or a proper laptop stand so the top of the screen is at eye level. Then you need a separate keyboard and mouse at table level or better still on a pull out tray like some computer tables have, so your arms can be at your side comfortably with shoulders relaxed. The seating position is also important so the feet are just in front of the knees, hips are above the level of the knees and good lumbar support [so a height adjustable chair with a lumbar support is ideal]. I'll do a video on this soon with some simple office exercises that can be done seated which i find invaluable. . meanwhile i hope this helps.