I love my treadmill. I am not allowed to run much due to knee injuries (overused) and this is why my PT said to get myself a bike as it is easier on my joints. Running outside may be too risky for holes, slipping, etc (especially being winter).

I can be on treadmill for an hour and loving every minute of it. But I am well equiped too. I have virtual running videos that are amazing and challenging. I have a huge sound system with the best music to run (at least for my taste), etc.

I do not run full throttle but more like fast babysteps to avoid the heavy pounding. I can't allow myself to injure my knees again. This seems to work well so far. The pounding is also absord by the rubber/pounce of the TM floor. I'm not afraid of twisting an ankle, etc. So my confidence is running is much stable and enjoyable then outside. I have no pain vs running outside.

I do intervalls of running, hiking (I can do 10% grade) and walking. All good to me. Especially with being inside, no need to worry about the crappy weather we've had in the past month (cold, deep cold, freezing rain, over snow, then freezing rain again). I put on shorts and t-shirt and ready to train and hop into shower as soon as done. No waste of precious time.