The heels get me everytime!

According to PopSugar.com:

You wear heels all the time: They may look good, but they also may be doing damage to your workout. A recent study found that regularly wearing heels shortens calf muscles, which can lead to a stiff Achilles' heel and muscle fatigue. These issues can lead to injury or off days when you work out, so limit your heel-wearing to twice a week, especially if you are training intensely.

You sit too much: If you've got an office job, chances are you're in a chair for most of the day. But there are many reasons why you should take regular breaks to walk around and stretch out your limbs. For one, sitting a lot during the day has been proven to lead to earlier death — even if you do clock in time at the gym. But it also hurts your workout by making you inflexible and causing body imbalances. This can be especially true if you spend a lot of your time crossing your legs while you sit, which decreases circulation, causes lower back or joint pain, or exacerbates workout-related injuries, so make sure you pay attention to both how long you spend in a chair as well as your seated posture. Read our tips for sitting properly in a desk, and don't forget to take breaks throughout the day.

You eat too much (or too little) before a workout: You know you need to fit in a workout before you start your day, so you wolf down your breakfast so you'll have enough energy to face your routine. Unfortunately, eating too much can hamper your workout by causing cramps or making you feel sluggish. But not eating enough before a workout sabotages your efforts as well — it's hard to motivate when you aren't fueled correctly for an intense workout. It may take time to figure out which snacks work best for you; these pre-workout snack tips may help you find the right fit.

You're not getting enough sleep: Lack of sleep zaps energy no matter what you're doing, and it can be especially true if you're trying to hold your own in gym class. If you've noticed that the quality of your sleep has gone down lately, then it's time to make getting better sleep a priority. Finish up your evening to-dos earlier so you can go to sleep an hour before you normally do, and make sure you build in time to relax before drifting off to sleep so you'll be less stressed and more likely to stay asleep.