I love my iPhone and I love my MacBook. Sometimes the things we love can hurt us... 

I'm now suffering from RSI in my wrist and my thumb. Mostly my thumb due to the repetitive action of scrolling on my iPhone screen while holding it in my right hand. Add to that scrolling on the trackpad of my MacBook, again using my thumb on my right hand, and you have a recipe for disaster.

The reason I'm telling you this is that these things are so obvious, but I've been ignoring the signs for weeks... It's not until it hurts that we take notice.

If you start feeling pain from repetitive motions, whether from using your iPhone, or iPad, or the trackpad on your laptop, take notice and act on it before it starts to become a problem. 

And I'm sure that PCs and Android phones are just as likely to cause RSI, it's definitely not an Apple-only scenario. 

I'm resting my thumb by strapping it up so I can't use it (which doesn't half make typing this hard!) I hope that in a week or so it will be possible to use it without it hurting.  You can rest assured that when I get my thumb back I'll be changing the way I scroll on my iPhone - I have already started using a mouse with my laptop at home...