You always produce heat just by moving though, and your clothing also produces heat, and internal organ processes. By 37° if you aren't sweating and with three fans and a dry ice block underneath you may have anihidrosis.
25°C is the standard room temperature; it's where pretty much all lab measurements are done (formation entalpies, entropies, Standard potential, the list just goes on). It is a perfectly comfortable temperature. 20°C is refreshingly cool. 0°C is absolutely fantastic.
Farenheit is based on the temperature of the lowest ring of Hell; that's the only explanation for it even existing.
[°C] = ([°F] − 32) × 5⁄9