Inclusive Human-Centric Software Engineering (HCSE) research faces significant challenges in recruiting participants from underrepresented backgrounds, including gender, race, culture, socioeconomic status, disability, religion, sexual orientation, and age. Our study explores the recruitment barriers encountered by HCSE researchers through in-depth, semi-structured interviews with 20 professionals from academia and industry across four continents. Using an inductive approach and open coding of transcribed interview data, we identified 25 key barriers and 20 strategies, categorized into five thematic areas: participant skepticism, study design limitations, logistical and financial constraints, gatekeepers, and researcher well-being. Notably, researchers highlighted barriers such as deteriorating mental health, external criticism of their research focus, and participant reluctance rooted in historical exploitation and perceived risks. To address these challenges, we offer a set of 20 evidence-based, actionable strategies aimed at improving participant outreach and enhancing recruitment practices. Our research culminates in a comprehensive framework to support both novice and experienced researchers in overcoming recruitment barriers, fostering greater inclusion and equity in HCSE studies.