The most important behaviour you should adapt and work on should be self-discipline.  That's really the most important aspect of training because everything else goes along with it.  Without self-discipline, you don't go to the gym and you won't stick to your workout routines. Self-motivation goes along with self-discipline because besides being disciplined you need that motivation to get you to the gym.

Diet. You can find everything about eating online,  you can find exercise routines online and there are tons of apps for the same purposes.  

You should eat at least 3 times a day that is a healthy intake,  however, you can eat it up to six times a day.  Depending on your body (BMI) weight and height there's a certain amount of calories that you should at least take daily to maintain healthy bodily functions but to sum it up three to six times a day.  if you want to gain weight find out how many calories you should be taking in daily according to your body weight. 

Determine your calories, weight loss or gain, choosing the workout routine that fits your goals will add to that.  If you want to burn more fat, look at exercises like high-intensity workouts or cardio combined with weights,  and weight-training tones the body more than cardio.  women do not have to worry about bulking by doing a lot of weight training to the extent of looking like a bodybuilder because you don't have enough naturally produced testosterone for that, a healthy male has 30% more testosterone than a female, so don't be scared to try weights.

Personal trainers. Find one that it's cost-effective, have good credentials and a good track record and one that specialises in what you are trying to achieve.

Hydration. Keep an eye on the colour of your urine if it darkens, drinks some water and if it's clear you are still well hydrated.  If you like to drink coffee or drinks with high caffeine you will have to increase your water intake. A good rule of thumb depending on your workout intensity and fitness level would be to rest 20 to 24 hours before your next workout.

Fasting has amazing benefits.  It helps to reset your mitochondria which then leads to your body getting rid of old and poor functioning cells. It also helps with your metabolism so your body makes better use of the food or nutrients that you eat. Track your energy levels and weight gain or loss be that muscle or fat. Tracking results takes a lot of time because you have to at least try it for a month to be sure. 

Muscles are made of protein. there's absolutely no disadvantage in taking in protein. that is with moderation too much protein could cause weight gain and I mean fat cuz it's directly related to calorie intake.

Brands we recommend are NPL, Nutritech whey protein,  Nitro tech from Muscletech.

Indoor training at home. There are many apps that you can use to train,  some of them have actual examples of how to do a specific exercise some of them just tell you how to do it.
We recommend Nike NTC it's a very good app that we prefer to use training indoors.  The type of equipment you need will vary. We recommend having a rubber mat, a skipping rope and weights. 

During the lockdown, I learnt that it's always a good thing to have one or two weights laying around you never know. Rotate training major muscle groups to prevent overworking. Remember to check with your doctor what kind of exercises you can and cannot do and supplements you may take.

Mental health. The beauty of dopamine and other endorphins the brain releases when exercising. Woke up on the wrong side of the bed.  Exercise. Stressed about work and finances. Exercise.

It's a simple equation if exercise makes you feel and think better only for a day it would make sense to do it every day. Start with a small goal and increase a little every day or week.