For this, you can add some pure eucalyptus extract in small amounts, or just add some drops of eucalyptus essential oil drops. (natural-holistic-health.com)
I've used a mixture of water and lemon eucalyptus essential oil in a spray bottle. (annmariegianni.com)
I also love Vitruvi Organic Eucalyptus Essential Oil, it's great used as a chest balm, in a steam bath / shower, or via an aroma diffuser. (shinesoulbright.com)