what would be an appropriate sample size for the following and why:

The convenience sample of 60 individuals was recruited from MS Centers and the National MS Society. The variables were measured prior to starting the creative art program and following the final session (pre and post). The instruments included the Rosenberg Self-Esteem Scale (SES), the Herth Hope Index (HHI), the Modified Social Support Survey (MSSS), and the MS Self-Efficacy Scale (MSSE).