Flexible nonlinear periodization (FNLP) was designed to optimize sport-specific resistance training by matching bout demand to pre-exercise mental and physical states ("readiness to train"). Before applying this participant-responsive framework to aerobic prescriptions for inactive adults, operational definitions of readiness are needed. Purpose: To identify themes underlying readiness to perform aerobic bouts considered to be low-demand bouts (LDB) and high-demand bouts (HDB) in adults with obesity. Method: Using Qualtrics, 1,059 respondents initiated the online survey. Quality responses from adults with obesity (N = 112) were analyzed. Respondents described physical and mental states necessary to complete an LDB (10-min slow stroll) and an HDB (60-min jog). Data were assessed using content and thematic analyses. Results: Respondents (57% female) could be classified with class II obesity (35 ± 5 kg/m[superscript 2]) and were 48 ± 12 years old. One theme, body integrity (no pain//illness) emerged for both the LDB and HDB. Regarding affect/arousal, both bouts required the need to feel rested and in a positive mood, but the HDB required higher states of arousal ("pumped up"). Specific to the LDB, a recurring theme suggested that it could be completed under normal or worse (hungry, sick) circumstances. Specific to the HDB were themes relating to physical fitness, proper fueling ("hydrated," "not hungry but not too full"), and enhanced motivation ("determination," "focus," "confidence"). Conclusions: These uncovered themes provide empirical evidence to guide the construction of a readiness checklist that can be further validated and applied in adults with obesity undergoing an FNLP-based aerobic exercise prescription.