Keyboard and mouse placement affects every minute of computer work. You do not need to pin your arms into one position. Instead, arrange the input area so your shoulders can stay relatively relaxed, your forearms have room to move, and the devices are close enough that reaching is not your default.
Put the keyboard in the working zone
Place the keyboard directly in front of you when possible, with enough clear desk space that you are not pushed back by papers or a laptop stand. Adjust chair height and keyboard surface together: if you have to lift your shoulders, press your wrists hard into an edge, or perch at the front of the chair, revisit the arrangement.
Keep the mouse near the keyboard
The mouse is easy to overlook because it moves so little on the desk, yet a far-away mouse creates thousands of small reaches. Keep it on the same level and close to the keyboard. Move the whole input area closer before trying to hold your arm in a more controlled position. If you switch between mouse, trackpad, and notes, clear a path for each task.
Make tools fit the task
Frequent number entry, design work, gaming, and writing use devices differently. Adjust the layout around the tool you use most, then move the secondary device only when needed. Keyboard shortcuts, a document stand, or a different pointer device can reduce repetitive reaching for some workflows, but there is no one required setup.
Check the chair and screen together
Input placement only works in relation to the rest of the workstation. The office chair setup guide covers height and armrest choices, while the monitor height guide helps you avoid trading a closer keyboard for a screen that is hard to view.
Reset between blocks
Hands and attention both benefit from a brief change after concentrated work. Stand, look away, walk, or switch to a non-screen task at a natural transition. See desk-breaks for posture for simple ways to make that repeatable. Seek individualized guidance for persistent or concerning symptoms, especially after injury or with numbness, weakness, or pain.