You have to do Physical Exercises for maintaining your Body.

What will you for maintaining your Mind and Spirit?

The exercise for Mind and Spirit is called Meditation.

Meditation is a combination of Science Art and Spiritual Practice.

There are many types of Meditations:-

• Breath Watching Meditation:-

By closing your eyes and sitting in any comfortable manner, you can watch your breathing; breathing in and breathing out; how you take in/inhale air into your lungs and how you let out/ exhale

• Empty Mind Meditation:- 

You have to keep your mind empty.

That is you try not to think on anything and keep your eyes closed and try to be calm and empty your mind.

You have to sit with your legs crossed or in Lotus Position for doing this kind of Meditation.

• Walking Meditation:- 

You do the above two types of meditations while you are walking; it is somewhat difficult to perform because of the distractions you will have while walking

• Mindfulness Meditation:- 

It is an art of becoming deeply aware of what is here right now.

You must focus on what is happening in and around you at this very moment, and become aware of all the thoughts and feelings that are taking your energy from moment to moment.

You can start by watching your breath, and then move your attention to the thoughts going through your mind, the feelings in your body, and even the sounds and sights around you.

The key is to watch without judging or analyzing.

• Simple Mantra Meditation :- 

You will find it easier to keep your mind from wandering if you concentrate on something specific.

A mantra or prayer will be helpful in this.

The mantra may be some words or phrases you repeat for a number of times, as you sit in meditation or walking and meditating.

In various Religions they have recital of repeated Mantras, either aloud or within their minds, which is similar to Simple Mantra Meditation.

The Mantra need not be religious; simple phrases on anything can be the Mantra for this type of Meditation.

• Concept Meditation :-  

Some Meditations involve contemplation of some idea or concept. For example you can medidate on "Impermanence," in which you will focus on the impermanent nature of all things, starting with your thoughts and feelings as they come and go. In the "Meditation on the Corpse," you will meditate on human body in the ground, as it slowly rots away and is fed on by worms

• Yoga:-  

Yoga is a Meditation added with Postures of the body, and hence it is a combination of Physical Exercise and Mental Exercise.

There are so many Asanas in Yoga.

Related readings:-
1.Breathing Techniques
2.Yoga for Weight Reduction