07/09/2017: "It has to be the same"
If you're training for fun, then train for fun. Divide things between training and not-training. Have two selves, two lives. A mental shift when you walk in the door and walk out again. Draw a line. Just like you do between work and not-work - you're a different person in each, right?
You may separate what you do at work and what you do at not-work, but you are the same person in both places and deal with things the same way in both places.
In the same manner, there is no divide between training and not-training. There can't be. Because the attitude with which you train - the focus, and both the mental aspects of the training itself and your approach to it - is also a part of the rest of your life.
At our school, we practice not only bujitsu, but budo. Both are often loosely translated as "martial art", but there is an important difference. Remember first of all that these are "martial" arts - "martial" deriving from Mars, the Roman god of war. They were first developed for and tested on the battlefield, and even many styles which were developed more recently still have these roots.
The -jitsu suffix pertains more to the physical part of fighting - for us, self defense, rather than offense or competition - while the -do suffix pertains more to the mental aspect, and can also be seen as a way of life. (Not in the same sense as in feudal Japan, but in terms of a mental approach to life.) We talk all the time about the mental aspects of self defense.
You can (and should!) have fun while training, but if you make a strict mental separation between training and not-training, then that creates issues. It changes your attitude toward your training, and potentially sets you up for failure during an actual encounter.
People do come in and train even when tired, or unhappy with work or with personal things (we'll use "tired" for short) - keeping even more attention to their techniques, because those mental distractions make for fraying around the edges because of lack of attention. Not doing a technique to the best of your tired ability simply because you're tired and it's not an actual attack is a distinction that cannot and should not be made.
If you don't train with proper form and attention even when you're tired (etc.), you won't be able to defend yourself properly, tired or not. Making a distinction between the two sets you up for failure - and not just at the dojo. If you're training for (in our case) self defense, you train for self defense, regardless of time or place. And though we come and bounce each other around a lot, most of the training, quite frankly, is mental.
Have fun, but train with focus and purpose regardless - and you'll find it's actually a part of the other aspects of your life. Whether you're at dojo, work, or home, it's mental. It's all mental. It's all one, everywhere.