Start w/ your diet. Nothing wrong w/ caffeine, generally. But, if you're having coffee every day at work, have it black. sugary energy drinks/soda/fruit juice - no more. carry your water bottle around. start to see food as a source of fuel not a source of pleasure. if anything, allow yourself something sweet right after a workout, just before your protein shake. also, have something healthy to eat as soon as you wake up and make it easy for yourself.. have it prepared. personally, i like having it be the same thing every morning. protein shake, hard boiled eggs and baby carrots. getting hungry is dangerous for you right now, because you will crave sugar. it's addicting. avoid it and keep healthy snacks w/ in reach. - as far as your workout focus on the large parts of your body; legs, chest, and back. But, first, make it cardio heavy to lose weight/burn fat..then you can transition to a more resistance training workout to build strength. swimming since your gym has a pool is good since it's easy on the joints. Swim 5 laps, get out of the pool and do as many push ups as you can right there next to the pool, swim another 5 laps then do squats, no weight, like 50 even if in sets, swim again, push ups again, swim again squats again. And, swim w/ a purpose, time your laps if it helps. Give yourself 2-3 weeks of this (5 days a week) to really get going. And, go for 45 min workouts w/ a really good deal of intensity. Don't go for an hour or more at an easy pace. After those 3 weeks, start w deadlift with really light weight(check form on youtube,) it'll provide a good base to start your actual workout routine and great for your abs and posture. Instead of doing that pool routine for 5 days a week you can move to about 3 days of cardio, 2 days of lifting. So on 2 days, separated by a cardio and a rest day, you'll deadlift light weight for 4 sets by 20reps (it should start to feel somewhat heavy by rep 20,) then do a back routine consisting of pulldowns 3x20, and seated rows 3x20 and a chest routine consisting of 3x20 dumbbell press flat and 3x20 incline (again, light weight that starts to feel heavy around rep 20.) This will be your workout for two weeks, then you're ready for a steady lifting workout week. There are plenty out there, but get to this point first. Personally, i like Day (1) Legs, 2 chest, 3 rest, 4 back, 5 shoulders, 6 arms and abs, 7 rest. There are a myriad of different workouts. When i'm not using this framework i'll do the superman workout by Jim Stoppani. I know you mentioned you're not looking to get buff, but you want to strive for that in all honesty.. at least, somewhat. not in an i want to be a bodybuilder now sort of way. but, it's like shooting for an A on an exam, if you miss by a bit you still get a B. If you're shooting for a C and you fall short by a bit, you end up w/ dad bod. aim high.