I think some people just find the turbo easier than others. I am a complete pussy in the cold and tend to hide inside a lot. I'd always prefer to ride outdoors and do where possible but I have no problems sitting on a turbo for several sessions a week if needs be. I honestly don't ever have any motivation issues, I love it. Some people really hate it. In the same way I hate the idea of a MTB!
My week looks something like
Mon- 90 min ride am, 60 mins pm plus 45 min run lunchtime
Tuesday- speed running session (hour) plus body pump am, 60 min ride pm
Weds- 90 min ride am, 45 min lunchtime run, turbo session of death pm
Thurs- 2 x GRIT classes am, spinning lunchtime (though don't go hard), running club evening
Friday- turbo session of death am, run and body pump pm
Saturday- 2+ hour run
Sunday- long ride (4-7 hours)
I tend to do this year round really, (Oct and Nov are easier months with less interval stuff) except when spring/summer comes, things get taken out/moved for racing. If I race on a Saturday (running obv this time of year) I move the long run to Weds morning. If the weather is shite, I will do all the rides on a turbo and be fine with it. There are only 2 'proper' turbo sessions in my week though, plus a running 'session'