Plant vegetables or sweet peas and climbing roses if the wall is in your garden. Salvage trees and plants from city and suburban demolition sites. Take them home and plant them or give them to friends. Plant in woods, verges etc. We need the oxygen!
Herbs can be used extensively for medical, culinary, mineral-giving, companion planting, pest-repelling and compost-making purposes. You have a bruise? Rub it with a comfrey leaf. A cut? Lay on a calendula leaf; fancy a cuppa - the choice is yours, year round.
Save water by bathing with your partner or enjoy bath-time with your young children. Save baths for special occasions or after stressful days. Put the plug in from the beginning to save water (the hot water should warm up the initial cold water). Fill up a couple inches below full. Use eco soap / bubbles and save the water to use on gardens, or use the still pretty-clean water to pre-soak heavily soiled clothes.
Don't make the mistake of putting your recycling in plastic bags before dropping it in the bin. Plastic bags are sent to landfill, often containing the recyclables inside.