The calculated distance (air line) between Lenart v Slov. Goricah and Velenje is approximately 37 miles respectively 60 kilometers.
By car or train, the actual journey to Velenje is certainly longer, as only the direct route (as the crow flies) between Lenart v Slov. Goricah and Velenje has been calculated here.
Air line (approximately)
60 kilometers
33 nautical miles