This may be a crappy tip, but it works for me and I thought that maybe it could help some other people out too:
When I feel sort of down for whatever reason and my confidence needs a boost, I picture a thermometer or speedometer in my mind. I try to pretend that the measuring device is in fact a confidence meter, a sophisticated mechanism used for the sole purpose of measuring confidence. I estimate where my current confidence level would be at and then concentrate really hard on bringing it up as high as I can. You really have to picture this and concentrate on what you're doing (this sort of tricks your brain into making you more confident). Its effects can wear off over time, but it's great for a quick confidence boost. Give it a try.
When I feel sort of down for whatever reason and my confidence needs a boost, I picture a thermometer or speedometer in my mind. I try to pretend that the measuring device is in fact a confidence meter, a sophisticated mechanism used for the sole purpose of measuring confidence. I estimate where my current confidence level would be at and then concentrate really hard on bringing it up as high as I can. You really have to picture this and concentrate on what you're doing (this sort of tricks your brain into making you more confident). Its effects can wear off over time, but it's great for a quick confidence boost. Give it a try.