A hobby can be said to be an activity which is done more than often by a person during his/her leisure time for pleasure. Meanwhile, lifestyle can be regarded as an individual's way of life. However, hobbies could change as time goes on but lifestyles are not easily left behind or droppedWorkout can be turned into a hobby and it can still be a way of life. I would like to look at working out from two distinct perspectives:

1) As a Hobby: When treated as a hobby, it is kind of impossible some times to do it regularly as it has to be done during your 'leisure time' and for 'pleasure' and you could be occupied with work or any other thing several times that could take up your leisure time. But any time you are chanced to work out you do it with so much pleasure and also use it as a way of blowing off some steam which is not always the case when it is regarded as a lifestyle

2) As a Lifestyle: When treated as a lifestyle, you cannot just do without it (it's become like a routine and seems much more like a monitored activity) and you need no leisure time nor derive any pleasure doing it most times but you still have to do it because it is part of who you are and it sort of completes your being. The same way you cannot do without other parts of your life, working out also becomes that to you and you try as much as possible to make everything about and around you act as instruments to helping you work out every day even when your whole schedule is tight and not accomodating at all.
From my point of view, I would like to think of work out as both a hobby and at the same time, a lifestyle. What's your take?