If you can’t make it to the gym, there’s no excuse not to workout at home. If the idea of a HIIT workout with just your bodyweight makes you want to scream and run away, I’m with you. Here’s some essential gym equipment that you can keep at home for the days when you can’t make it to the gym and are not about to drop and do some burpees.
Cushioning
You need a gym mat to protect all things knobby from the floor. This is not a yoga mat.
A gym mat is more cushioned (mine is 1/2 in. foam) with less emphasis on gripping the floor, and is more comfortable for ab and glute work on your back. If you exercise at home and you don’t have a gym mat, buy one. It will change your workouts for the better. Commandos are torturous by nature, but you don’t have to suffer the bloodied elbows that accompany them sans mat.
As an aside, if yoga is your thing and you’re in the market for a home yoga mat, I suggest the GRP yoga mat from Manduka. It’s cushioned enough for poses on your knees and back, and it does a great job of gripping the floor. I carry mine ten minutes or so to and from the gym with me, but it weighs 5 lb and will serve you better as a mat for home.

Fitness mat by Fitness Gear 
GRP yoga mat by Manduka
Weight
Adjustable dumbbells and kettlebells are the answer to storing home gym equipment without a true home gym. IronMaster makes dumbbells, kettlebells, and plates to adjust their weight that can be readily locked into place. If the 45 lb (per dumbbell) set isn’t enough weight for you, you can buy additional plates that will increase the weight of your dumbbells to 75 lb or 120 lb (per dumbbell).

Quick-Lock Dumbbell System by IronMaster 
Quick-Lock Adjustable Kettlebell by IronMaster
Bench
The Reebok Professional Aerobic Deck is everything you need in a gym bench. It’s sturdy enough to step up on, can be used (flat or raised) for lifting, and has legs that fold in so that it can be slid under the bed and out of the way.

Professional Aerobic Deck by Reebok 
Professional Aerobic Deck by Reebok
Resistance
Black Mountain Products makes great resistance bands to intensify your home (or gym) workouts. They also come with a bag, so your resistance bands aren’t loose in your gym bag!

Loop Resistance Exercise Bands Set by Black Mountain Products 
Stackable Resistance Band Set by Black Mountain Products
None of the above products are sponsored. These are genuine recommendations based on my personal experience and the equipment that I keep at home.