How do I increase my self-confidence at work in front of my managers and clients?

If you know your work very well, confidence will come naturally to you.  If you think you are weak at one area of your job, you need to concentrate more on that area until you mastered it.  A good start would be, accepting your weakness wholeheartedly and be able to accept constructive criticisms from your peers.  You need to be very patient with yourself, as the process of increasing self confidence is not overnight.

Gaining self confidence mostly depends on:1.
Through knowledge about the job.2.
Making some effort of practice even the job is very small but with limited time period.3.
Saying No with a positive try to learn it in case of not being confident on the job assigned.4.
Thinking about the responsibilities with a view to improve it.

you have to go through all aspects of your work and do your best with your knowledge and skills,so you can complete your work with satisfactory.your seniors will also trust you and give more work after seeing your dedication to your work.

Increasing confidence in one's own self is mostly a Psychological game. Also it requires having a "backbone". The mind is just like a muscle, we must work it out. Here are some tips I'd like to offer:

1. Believe in yourself and your own abilities and skills

2. Learn to manage your efficiency (Don't try to be over efficient or under, balance it out)

3. Try to increase and enhance your professional skills and knowledge. The more tools you have at your disposal and with the rise in your work potential your confidence is likely to increase.

4. Don't allow others to push you around beyond moral limits.

5. Try to stop and avoid negative thinking.

6. Always try to be ethically and professionally sound i.e. Cover your tracks and always follow the professional code of conduct. When you perform a job, do it well in its entirety. If you've done a job properly covering all aspects in line with professional conduct, you need not worry much over a negative outcome or becoming the point of blame as your effort will justify and speak for itself. Failures cannot be pinned on you without a solid reason.

7. Try to be passionate and positive about your work. Allow yourself to enjoy in the work environment while staying professional. Build good relationships with colleagues and associates etc.

8. Even when faced with failure or criticism try not to let it get to your head. Mistakes can happen and the best way to counter it is by trying to mend them and avoiding them in the future. Learn from them.

I once read a very good quotation by my favourite novelist i.e. Mr. Jonathan Kellerman (Famous New York Times bestselling author) who stated that "Every crisis is productive, we get to walk away with catastrophe".

1- doing my job
2- fulfilling the tasks
3- finding ways to enrich my knowledge
4- reporting weaknesses and strength
5- SAYING I DON'T KNOW WHEN YOU DON'T KNOW