There is no doubt that pushups are simple and practical exercises that can be done anywhere. If you do 100 pushups every day, your body will be adaptive to it. Once you expose your muscles to the same type of stress, they get used to it and stop going more significantly and more vital. Doing 100 pushups in a day will need some recovery time. It would be better to do a variety of exercises in your workout.  All these exercises are bodyweight exercises and don't need any equipment. You can do them at home also. People of all ages can easily do these exercises.