In the vlog "How to Believe in Yourself (Even if No One Else Does)," Aileen Xu shares strategies for cultivating self-confidence, even when external validation is lacking. She emphasizes the importance of trusting your own abilities and staying true to your vision, regardless of others' opinions. Aileen encourages building self-belief by setting small, achievable goals and celebrating progress, which can create a positive feedback loop. She also stresses the power of affirmations and surrounding yourself with supportive influences, reminding viewers that self-belief is key to pursuing their dreams and staying resilient in the face of doubt.