Exercise start 101 sugestions requested

 I started working out at 8 weeks post op RNY and was still not getting enough calories to compensate...I was soooo exhausted and hurt near my surgery scars.  Had to go back for a biopsy, and am just now ( 3 1/2 months out) getting back to the gym....any suggestions on what I should be doing....I left it up at first with my trainer, and would like to hear first how others started out...if just walking, how far, how fast (I was doing 2 miles right off at 3-3.5 mph at an incline of 2.5 - 5%.  I felt that I had shin splints (yes...I now remember how I first got those when I ran 6 miles a day...lol). I want to be smart, not wimpy but not unrealistic either...All suggestions are welcome...and thanks in advance for sharing.

Personally, (and looking back on my own last nine months post surgery), I would concentrate on weight training first then do some cardio after.  I started out with the machines circuit at the gym and when I had mastered that I moved onto free weights.  If you have some help (free training session, etc.) I'd ask someone to set me up with a free weight workout that utilizes your arms, chest, back, legs, core.....and alternate days.  Maybe start out with 20-30 minutes of weights and 20-30 minutes of cardio then up it from there.