The main purpose of this study is to evaluate the safety and tolerability of LY3873862 when administered either in single or multiple doses in healthy participants. The study will also assess how fast LY3873862 gets into the blood stream and how long it takes the body to remove it. The study is open to healthy participants. The study will last up to approximately 58, 72, and 72 days for Part A, B, and C, respectively.

Inclusion Criteria:

• Participants who are overtly healthy as determined by medical evaluation
• Body mass index (BMI) within the range 18.0 to 32.0 kilograms per meter squared (kg/m²)
• Are male or female participants, including those of childbearing potential

Exclusion Criteria:

• Have a history or presence of medical illness including, but not limited to, any cardiovascular, renal, hepatic, gastrointestinal, respiratory, hematologic, endocrine, psychiatric, or neurological disease, convulsions, or any clinically significant laboratory abnormality that, in the judgment of the investigator, indicate a medical problem that would preclude study participation.
• Are unwilling to comply with the dietary restrictions required for this study, including the avoidance by 5 days prior to study drug administration until the final ambulatory visit the ingestion of fruits, sauces, and juices containing furanocoumarins that irreversibly inhibit cytochrome P450 (CYP)3A4. The following fruits, sauces, and juices are excluded: grapefruit, Seville oranges, pomelos, cranberry, Goji berry, and apple.