To feel regret or sadness over the potential loss or waste of something valuable, whether it be time, effort, or resources.
To hold back from using or giving more than necessary, often reflecting a desire to preserve or cherish what one has.
To feel a sense of reluctance to expend one's energy or resources, particularly in situations where one wishes to conserve them.
To express a deep appreciation for something and to be unwilling to part with it, often infused with affection or tenderness.
To lament the passing of moments or opportunities, feeling a longing to hold onto them rather than let them slip away unnoticed.
Example:
ほとんど弁当を食べるひまも惜しんで勉強した。
It is regrettable that something unfortunate is the case.
It is a pity that circumstances did not turn out favorably.
I find it disappointing that a given situation lacks a positive aspect.
It is lamentable that things did not align as hoped or expected.