Easy answer: the extra time spent every day helping my daughter with her homework. This has paid off enormously. Not because she's a grade-A student (far from it; she has a lot of difficulty). But because I've been able to consistently, calmly teach her the following skills that I'm now starting to see her pick up:

1. Everything looks difficult the first time. The hardest step is always the first one. Take a deep breath and just "begin".

2. Never give up. Even impossible tasks are just lots of easy, smaller tasks. Learn to break things down into manageable pieces.

3. When in a time crunch (e.g. a test), learning to triage is a very important skill. Don't get stuck. Just skip and move on. Come back later. Learn to prioritize, etc.

4. Don't be scared. Everyone gets it wrong sometimes. You'll never succeed if your too afraid to fail.

5. Trust your gut. If something seems wrong, then it very well may be. Don't just accept someone else's answer because you don't happen to know the answer.

6. Always verify your answers. Don't just finish a problem and assume it's right. And learn to verify the answers of others as well.

Finally, never ever ever say "I'm not good at that." Say "I'm not good at that YET!" That little difference over time is reminding yourself that you could learn/do it if you wanted, you just haven't learned to yet.