You can join a gym perhaps? They have heating and lighting and it has the added bonus of not having a dog chase you. However, there is also the inconvenience of getting there, the gym membership can be costly, it tends to get monotonous, the machines you want to use are either occupied or plastered in the last person's sweat. Also, if you are training for an outdoor event, you can't beat training outdoors for it.
Running on a treadmill is not the same as running outside ... I know that sounds like an obvious statement, but for example, your running gait tends to be different and so does your weight distribution. This means that if you make the mistake of transferring from treadmill training to straight away running in a race on tarmac or uneven surfaces, you increase your chance of injuries, particularly shin splints. Treadmills in gyms tend to have a good deal of shock absorpancy, which you don't get running outside on hard surfaces, you have to condition your muscles for this, and the best way is by running OUTDOORS. Try varying your terrain and not running the same route each time.
Of course being outside means that you have to hardcore the outdoors. Wearing the right clothing helps, investing in a lightweight headtorch also solves the lack of light problem. Finding someone who will run with you if you are scared of the dark, or even someone on a bike leading the way is an option.
When you run outdoors in hideous weather, you have to embrace it, enjoy the challenge of beating the elements - no really, it can be fun!! You need to not dwell on the idea of it, because you will start talking yourself out of it.
You will enjoy it once you are out there, you just have to GO. The best thing you can do is, if you run before work in the mornings or college etc, when you get up, put on your running clothes straight away, even before the first toilet trip of the morning, so that you have no choice and your brain has to accept you are going out for a run NOW.
Or if you run after work, don't think about it, just change instantly into your layers of running clothing as soon as you get home, put on some motivating music, grab your headtorch, and just go, (leave those snacks alone!).
The training I do for my desert runs is largely mental, I run six days a week no matter what as a minimum. On my running day off, I always cross train.
I run this much because it conditions my body into recovering faster. This enables me to do events that require you running an average of a marathon a day or more over several days. The training you do will depend on what you are training for. The training I do is specific for the events and kind of running I like to do, which is long distance and off road.
Never go from never having run before, to running six days a week though, you need to build this amount of running gradually, it may take weeks if you are lucky, but usually it takes months.
My next event is in May, over the next five and a half months my training gets more intense, I will end up running an average of 125 miles a week several weeks up to the event.
You don't have to do this sort of training however to just get through running everyday for a week in a self sufficient run in 50 degrees Celsius.
I proved this by doing no real training whatsoever for the Gobi March, a 150 mile self sufficient run with Racing the Planet in March 2010. I had planned and entered to do it in 2009, but I had broken my back in December 08, and had only learnt to walk again in March 2009, so had deferred the entry.
I still couldn't run outside in November 2009 because of the nerve pain I was getting and the paralysis in lower parts of my back. I managed about one run a week outside from January 2010, the rest was laboured jogging on a treadmill, having to hold on the majority of the time as my balance wasn't great.
In March 2009 though, I succeeded in running most of the Gobi race and somehow I won my age catergory and got fastest British woman. What I am trying to say is, if you want to do something enough, you will find a way of doing it.
Training is largely a mental game. Having someone encourage you is a huge bonus too. I was lucky enough to have a 14 year old son who cycled with me during my rehabilitation. He would join me even at 6am in the morning, before he went to school, on the exercise bike, just to motivate me. He cycled for an hour and I jogged on the treadmill for an hour. I learnt alot from his support.
When I run with clients I realise just how important having that support and just how important encouragement is. We don't always know what we are capable of, sometimes we are never brave enough to try.
It often takes someone else to see our potential. So go on and get out there and test yourself ... if I can do it, absolutely anyone can!