Personal and professional relationships:
Without explicit feedback, by being attentive to the reactions of others. Not just their words, but their physical reactions and body language as well. If you've disappointed a manager, you may not get a statement about it from them. But you'll see it in other ways:
- Do they greet you like they used to?
- Do they give you the same kind of assignments/tasks? More responsibility, less responsibility?
- Do they, unprompted, solicit advice or ideas from you more often or less often?
- Watch their facial expressions when they see you coming down the hall of the office (obviously easier in years other than this one). Do they "put on" a pleasant face or does it seem to come naturally?
Same thing when dealing with other people in this regard. Romantic partners, family members, friends, acquaintances.
And be willing to solicit feedback. If something seems off, ask about it. But be open to potentially negative feedback. You cannot be defensive if they say something hurtful, you solicited it.
Habits and productivity:
For things like habits or productivity, you can gauge yourself fairly well with a logbook/journal. Write down a "daily activities" note. "What did I do today?" Then review it at the end of each week to make a weekly activities summary, and review that monthly for another summary. And compare the weeks and months against each other. "Hmm, these were 5 simple tasks and that's all I accomplished this month, but in prior months I finished harder ones. Was the work lighter this month with the holidays or did I do something different?"
Self-criticism versus self-inquiry:
Look into CBT (cognitive behavior therapy). That turned my life around from suicidal depression to actually being (mostly) satisfied and happy with myself and my life (mostly because there are areas I want to improve, but I'm not loathing or hating myself anymore). Find a therapist/counselor with the specific goal of working on this skillset.