The effects of three different procedures, relaxation, visualization and yogic breathing and stretch (pranayama) on perceptions of physical and mental energy and on positive and negative mood states have been assessed in a group of normal volunteers (N = 71, age range 21-76). Pranayama produced a significantly greater increase in perceptions of mental and physical energy and feelings of alertness and enthusiasm than the other two procedures (P < 0.5). Relaxation made subjects significantly more sleepy and sluggish immediately after the session than pranayama (P < 0.05). Visualization made them more sluggish but less content than pranayama (P < 0.05) and more upset than relaxation after the second session (P < 0.05). Thus, a 30 min programme of yogic stretch and breathing exercises which is simple to learn and which can be practised even by the elderly had a markedly 'invigorating' effect on perceptions of both mental and physical energy and increased high positive mood. A more extensive investigation is planned to establish whether such a programme can readily be incorporated into everyday life, and with what long-term results.