This is also one of the qualities of a chossid in the sense of a member of the Chassidic movement. Chassidus comes to promote a higher standard of observance, and so in addition to all the other aspects of being a chossid, a chossid is devoutly religious. Not only is he particular to follow everything in Shulchan Aruch, but he strives to go “beyond the letter of the law.” And he does so because the path of Chassidus infuses him with passion in his service of Hashem. Since the chossid yearns to come close to Hashem, he is constantly on the lookout for new ways and opportunities to draw yet closer, even if it involves spending time, effort, and money.
Examples of the above include following Chassidic customs that involve a stricter standard of observance: wearing two pairs of Tefillin; woolen Tzitzis; a full, untrimmed beard; and scores of other customs too numerous to mention.
By the same token, a chossid is extra careful to avoid anything that may somehow involve or remotely lead to sin.
The Chabad chossid in particular attains this sensitivity by studying the lengthy explanations in Chassidus of Hashem’s greatness and reflecting upon them, thus infusing him with a sensitivity to G–dliness and a desire to come as close to Hashem as possible. Since he knows that every extra observance constitutes a chance to come yet closer to Hashem, he seeks them. Conversely, this same sensitivity makes him naturally all the more careful to avoid sin, by undertaking chumros, extra precautions against sin (provided that doing so doesn’t simultaneously create an unacceptable leniency in some other area).
Thus, one of the answers to the oft-asked question, “What is a chossid?” is: “A chossid is a frummer (one who is very religious).”
Based on Kuntres Inyanah Shel Toras HaChassidus, p. 1.