Possible Clues:

• Register fewer details when lacking energy
• Tells sis to be lacking in energy
• Lethargic and disorganised on a shopping trip?
• Disinclined for effort and lacking the inclination?
• Not bending over because lacking the energy to?
• Uninterested, having no inclination either way
• Don't be so inclined to seem so uninterested
• Showing no enthusiasm, torpid
• Upright but lacking get-up-and-go
• Having neither the inclination nor the energy