These factors apply to many goals including: gaining muscle, strength, power, increasing cardiovascular capacity, endurance etc.

1. Sleep.

 Ensuring you're getting 7-8 hours of sleep is crucial to allowing your body to recover and rest from the stress and strain you're putting it through via exercise. If you don't rest enough, you might be fatigued and not able to put enough effort into your workouts. Or your muscles will not be fully recovered yet, they tear when you work them and need to be repaired before they tear again.
 If you have issues sleeping try: A meditation app, A new bedtime routine with no screen time 60 minutes before bed, Adding in 20 minute naps when you can, Try Melotonin to get into a proper rhythm.

2. Nutrition:

 Not eating enough, eating too much, etc. This can make you or break you and your fitness routine. If your body doesn't have enough energy/nutrients to fuel you through your workout it will be subpar. If you don't fuel it properly afterwards it will be unable to repair. Now depending on where you are in your training you might need more cards/more protein etc.
If you're having issues with nutrition: try tracking your macros with myfitness pal, Seeing a nutritionist, Meal prepping.

3. Stress:

 Stress can be both good and bad for the body, we need it to get the flight or fight response going, technically exercise is stress on the body, but too much stress can lead to weakened immune systems. Not only can it affect our immune systems and make us sick, chronic stress can create anxiety and depression, both which are going to inhibit your performances in the gym and in life.
Try: Cutting back in one small area, Taking 5 minutes to stretch in the morning, Try a meditation app, Schedule down time like you would a meeting (meaning commit to it), Go for a massage, Try other self care tactics you like

4. Load: 

Load meaning the actual work you are putting your body through with your workouts, sometimes we do too much or we do too little. Ensuring your workouts are balanced and in line with the results you want to see. For example, if you're looking to gain muscle you're not going to spend hours on the elliptical.
Try: Seeing a personal trainer :), Using a fitness app (I suggest volt, it can be more specific to sport), Keep a journal of the weights you're using/reps to see a change, or to track your runs etc.

5. Patience: 

Not giving yourself the time to see results, we all want results immediately and then are disappointed when we don't. You need to give your body 6 weeks to asjust to any training program before you can decide if it's working or not. Same goes with changing bad nutritional habits. It takes time, repetition, sometimes you'll fall off but you got to get back on.
Try: Again a professional in the area you're looking to change (nutrition, fitness, mental health etc), Keep a journal to track progress, Give yourself an end date where you'll reasses and go from there.


6. Have Fun!! 

You're never going to stick to something you hate doing, try to find a form of exercise you genuinely enjoy doing and it won't be such a struggle. Exercise and movement can be such a fun celebration of your body, so try to find things that make you feel that.
Try: All kinds of different workouts, different classes, obstacle courses, boxing, pole dancing, join a softball team, lift weights, run sprints, whatever makes you feel really good after or during.