Do what you can, be comfortable...

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If you are going to keep up a regular exercise pattern, long term, which is what will make the difference, make sure it fits your life. Whilst you have to make room for exercise, make sure it fits with work, family, weekends etc... Whatever you can do, however little that might seem, if you do it regularly and you can keep on doing it week after week, month after month, then that is what will make the real difference.

Oh and by the way, make sure what you do is FUN, if it isn't, you are unlikely to keep doing it long term. Put variety into your exercise plan, that alone will stop you become bored of the same old, same old. Walk, swim, gym, exercise classes, weights, mix it all up and keep doing it.

But above all enjoy and have fun!