Is judo wrong for me?

im a 40 year old man who (as of today) still smokes. I consider myself fit due to being ex military and still work out. I ran a mile 3 months ago... lol. Anyway i plan to quit in the next few days. I visited a martial arts studio today in search of a non traditional workout, plus ive dabble in it from time to time. However, being forty and a single parent of a 7 year old girl kind of changes things. I am looking for long term health and possibly, if i like it enough to attract her to it, a family thing to do with her. Anyway, i was very impressed with the instructor and the fact he has his 2 pre teen sons involved and competing in his dojo. I am now second guessing my age and ability to take the stress of Judo. Any thoughts?