Every day I like to two do types of exercises. I go for a walk for an hour and I like to lift weights. Walking gives me an opportunity to think about things, or to listen to an audio book. Lifting just makes me feel bad ass. However I wouldn’t say that I workout in sessions. I think about it as a daily thing. I just try to get it done before the sun goes down. This has allowed for a lot more flexibility with my schedule.
I think that no matter what form of exercise you do it has to meet two criteria for it to be effective. For me it has to be enjoyable and it should be measurable. If it’s enjoyable you will have no problem keeping at it. It’s even better when it is measurable, because then you can set goals and improve. Every time I lift weights I add either a small amount of weight or reps. It might not seem like much adding 1 or 2 lbs to the barbell, but after just 10 workouts you’ve added up to 20lbs to your bench press. It adds up.
When I go for my walks I don’t worry about the time it takes. I think about how far I can go because no matter how far I walk I will always be able to walk back. If you worry about how long it is going to take it might discourage you and you might quit early. If you can’t do a long walk you can do four 15 minute walks. Same goes for any exercise. If you can’t do one long session, then do short ones throughout the day.