The way you hold your body influences your state of mind (and vice versa). If you could use a little self-esteem or confidence boost, try an expansive posture that gives you a greater sense of power.
One pose you can do before or after an activity (such as if you have a big presentation to make or are about to propose to someone) is to stretch out your arms like you're going top hug someone. This apparently boosts confidence levels by increasing our level of testosterone.
Similarly, you can raise both hands with clenched fists:
Do it like you've got the power or you won with hard work.
See other poses you can adopt to trick your mind via the link below or "unleash your inner alpha dog" with even more poses.
5 Body Postures That May Actually Boost Your Self-Esteem [Dumb Little Man]