environmental conditioning

it's too hot, it's too cold, it's raining, it's not raining but it might start soon...
since the day humans have had to opportunity to choose if exercising or not, weather conditions represented one of the most used excuses for skipping an outdoor workout and remaining on the couch watching TV. many of our conspecifics, even if they train consistently, tend to avoid exercising outdoors if the weather conditions are not perfect. considering that in nature perfection does not exist and that the weather tends to change extremely quickly in many areas, this means avoiding outdoor workouts during a large part of the year, and that's a pity, as staying outdoors and exercising outdoors has a lot of benefits for our health.
let me go straight to the point. the most important benefit of exercising in cold weather is that it's the best way for conditioning our body to produce brown adipose tissue, a particular type of body fat that usually can be found only in the newborn and tends to disappear as muscle tissue develops during the first months of our life. the main function of brown adipose tissue is to generate heat burning white fat (the ordinary fat tissue that all mammals use to store energy and that we all know just as bodyfat), that's the reason why it's so important in the newborn: the main method that our species uses to generate heat is through shivering, but shivering requires the activation of muscle mass. if the muscle mass is very little, as in the newborn, the only way to generate heat is using brown adipose tissue. but nowadays, as we live the largest part of our life in places where the temperature is constantly monitored and adjusted according to our desires, our body does not produce brown adipose tissue anymore. that's the usual economic principle that applies to physiology: when something becomes useless, save your energy for something else.
still, some tests on people that are chronically exposed to cold weather proved that if we come into contact regularly with cold temperatures without being overdressed, our body recovers the ability to produce brown adipose tissue also during later stages of life. having a certain amount of brown fat tissue in our body proves to be crucial as it allows a better management of body heat and a speeds up the metabolism (basically, we'll burn fat easier). so, the best way to condition our body to produce brown adipose tissue is exercising in the cold feeling it. this means do not wear multiple layers of shirts or technical fibers that are engineered to keep us warm insulating our body. conditioning our body to produce heat through brown adipose tissue will also relieve our immune system from the extra work it's forced to do during during late fall and winter, when the effects of lower temperatures match with the higher quantity of pathogens we come into contact with, as we tend to spend more time indoors in crowded spaces (public transportation, cinemas). (note: if you're interested in this subject, you should read the book “what doesn't kill us” by Scott Carney).
in a similar manner, also exercising in the heat brings many benefits: it speeds up the function of the sweat glands and allows a better skin perspiration. so when it seems too cold or too hot for a run in the forest and many people choose to train indoors, my advice is to do the exact opposite. go out. it will condition your body more than your regular workout. at the same time, you will be training your mind and strengthening your temper. after a few times you'll become less prone to laziness and to the constant research of comfort.
we can't expect to live always in the safety and pleasantness of our comfort zone, it's life itself that from time to time forces us in situations of discomfort. i know that putting ourselves willingly in uncomfortable situations may seem an odd advice. in the name of civilization and progress we have built around us a cage of pleasantness and technology that keeps us safe from the menaces of wilderness, but at the same time it's making us weaker. so let's move in the opposite direction, one step at a time. a gradual and reasoned exposure to uncomfortable weather won't kill us. the same goes with rain. it's just water. our ancestors survived extreme conditions without heating systems or AC units, and all species living in nature are able to find their way to adapt to the environment. we can do the same as well, as we can still produce brown adipose tissue.  it will take just some balls to stand some discomfort and shivering, but working out outdoors when the weather isn't exactly as we would like will push the boundaries of our comfort zone making it wider, and in just a few sessions our body will learn to perform better in all conditions. our health will improve, our metabolism will become more functional and our spirit stronger. let's do it. it's just another trick for getting the most out of our daily workout.