I do have some experience in this area. Even for me, it is something that only happens occasionally, and usually only if I have a close tie with the individual, or the subject. It is not as reliable as I would like, but then many things are not as reliable as I feel they ought to be, and they are accepted with their faults.
If you want to strengthen this ability, there are three things you must do:
1) PRACTICE
2) PRACTICE
3) PRACTICE
With time you will find improvement. You may also consider keeping a journal to verify your experiences.
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