Okay i found a very cool trick that will help you to grind EXP without holding a button. This only works for Relax mode.

Step 1

While holding Space button, press the Shift + Tab button to activate Steam Overlay

Step 2

Release the Space the button while on interface. After you release you finger press Shift + Tab again to close Overlay

Step 3

Now you can grind Exp without holding a button, however when you press Space or Left Mouse button or switch apps, the hand will stop touching. That means you will have to stay away from PC or use the internet on Overlay. You can now touch the real life grass while you grind EXP.