These lightweight (and recyclable) aluminum cans come in two sizes: the 4" tall O+ mini holds 24 breathes per can (use 3-5 breaths per time), $8 USD per can; and the 8" tall O+ skinni with 40+ breaths per can (so 8-12 occasions per can), $12 per can.
You can buy O+ in 3 packs or get the Elevate pack which is a refillable delivery system. Easy to use and in three barely there "flavors," peppermint, grapefruit and natural. Learn more, find a retailer or order at OxygenPlus. Vic Braden is an ambassador for the company which says good things about the product. Please see the precautions on the O+ site if you have impaired heart or lung function or any other medical condition.
Nuun offers an easy way to carry your sports drink (or make more quickly between sets). Your essential electrolytes beverage is created by dropping one nuun tablet into 16 oz. of water. Nuun contains no sugars (sorbitol is used), is under 6 calories and delivers 360 mg. sodium, 100 mg. potassium, 25 mg. magnesium, 13 mg. calcium and more including vitamins.
The tablets (12 tablets per tube) come in 11 flavors. My favorites are the lemon or lime based. I like my drinks light tasting so I use 1/2 tablet per bottle. The tubes are $6.50 USD each (app .50 per serving if you use a whole tablet). Sport drinks are a must and I often forget to bring one along to the court. Keeping a tube of nuun in my bag makes it easy to make a drink in seconds since water fountains easily supply the base. Learn more or find a retailer at Nuun.
Deodorize that stinky bag of yours with this bamboo charcoal filled bag from Moso Natural. Simply toss the 6 x 7" linen covered sachet in your gym or tennis bag and smell the difference. The charcoal absorbs moisture and odor. Reactivate the bag's powers monthly by setting out in the sun. Each bag lasts two years and can be cut open and safely spread in the garden when done. Go green! The 7 oz. size will do you fine: $6.99 each USD. Find a retailer at Moso Natural.