Crank, I think it's hard any time you start something new but it's also great to mix it up and do something in addition to cycling. I've only been running about a year off and on and don't do over 5 mph on the treadmill and certainly don't run that fast outside. There are days that I feel invigorated and others like yesterday that I have to force my way through it--but I'm moving and not sitting on my duff on the couch. It also makes the winter go by faster. Take it slow and hang in there.