I love to swim but I am not sure if it is good on the body, do you know?
I love to swim too. Swimming is actually a low impact activity and compared to running is better on the body.
Do you work a lot of muscles? I know my body is normally tired when I am done.
Yes.  It's a great workout.  I suppose it's different for people as swimming relies on the natural buoyancy of the body.
Does it have any long term effects? Like I know running is bad on the knees long term.
No long-term effects that I know for sure, but since the human body is less dense than water, water supports your weight while swimming.  No negative impact to the body at all.
Is swimming great for all ages then?
Yes.  Swimming is consistently top rated for public recreational activities.  It's safe for all ages.
At what age do people generally learn to swim?
Swimming
Swimming is the self-propulsion of a person through water, usually for recreation, sport, exercise, or survival. Locomotion is achieved through coordinated movement of the limbs, the body, or both. Humans can hold their breath underwater and undertake rudimentary locomotive swimming within weeks of birth, as a survival response.
Swimming is consistently among the top public recreational activities, and in some countries, swimming lessons are a compulsory part of the educational curriculum. As a formalized sport, swimming features in a range of
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