I've always view Si as just pure internal sensations that you use to navigate the world and perceive it through a personal lens. AKA You lead with balancing your own personal sensations through manipulating the outside world to your own liking to please it or reach balance. For some people it is viewed as taking care of your health, or putting yourself in an environment that is right for you or going at your own pace that you see fit. Everyone is different and their internal sensation balance is different. I freaking hate wearing socks and that make me internally mad. Another person may love socks and it makes them internally happy. Both are right with their internal sensations, just need a different balance.
People stereotypical would assume heath with Si cause the person is naturally tuned in their own internal sensations then other types. Thus when feeling out of balance or 'sick' they would be hyper aware and would want to change it to feel more balanced. But, Si is very hedonistic and pleasure can over turn health. Hard liquor is bad for you but that's not going to stop me from downing shots and getting drunk. Cause right now, all I care about is feeling good and pleasurable sensations above all else. Consequences be damned! A smoker Si just likes the feeling and consequences be damned if it makes him feel internally feel good. Si users are less likely to repeat past mistakes if they had a bad internal sensation. They will remember it strongly and do not want to repeat it more then intuitive types. That is why they don't always need new options or may be sacred of change simply because of the possible bad sensation or bad experience and can get in ruts.
Also in ESE and SEI, Si is paired with Fe. Care taking is viewed as stereotypical cause Fe users are very in-tuned with the outside world of peoples emotions, reaction, harmony and objective moral perceptions. So you mix someone who is sensitive with their internal sensations with the reactions of the outside world, then they are going to want to naturally balance the environment to feel internally pleasant. I am more sensitive to it personally, so I tend to react more to it. Like I hear a crying baby and my immediate reaction is too sooth. It's messing with the environment and its making me feel like crap cause the harmony has changed. I find what it is internal sensations are, it stops and the harmony is balanced and now I can feel more balanced. Not saying that Fe is always care taking. Si with Fe can look like being a calming presence in a harmonious environment or being able to simply recognize emotional cues better in the environment quicker and understand them better. But there is both a focus on both internal sensation and extroverted feeling judgement.
I would include the MBTI with past and present but, I tend to naturally do that with all my internal sensations. You cant really imagine what a new sensation would feel like if you never had it. You can imagine but the body may not like the sensation or improve of it until it happens. Other then that, I always navigate like that.
Also, If we are going to talk about changing Si, then we have to talk about ISTp as well as they lead with Si. Si with Te can appear and look different. @
LemurianLo, How do you view Si?