| really (87) | different (30) | little (32) | activity (27) | actually (57) |
| pleasure (26) | something (57) | things (115) | release (74) | should (26) |
| important (30) | dopamine (506) | increase (71) | experience (47) | activities (36) |
| levels (48) | reward (38) | people (106) | motivation (36) | baseline (81) |
| because (79) | pathway (34) | increases (35) | caffeine (26) | system (30) |