Depends on what your workouts consist of. If you're doing about 1 hour of cardio, you can do it every day until your joints refuse to move.
If you're trying to build lean muscle and get all sexy-like, try to work different groups on different days(for example, shoulders/back on Monday, plyometrics on Tuesday, then biceps/triceps on Wednesday) or just skip every other day if you do full-body strength training. Either way, you're going to have to take a few days off every week to recover. Make sure you get in plenty of protein!
It depends on what your goals are and what the type of working out is. What are your overall goals?
Cardio can be done everyday. Resistance training (of one muscle group) should be done no more than once every 48 hours.
Regarding your abs, its likely that's just your trouble spot and you won't begin to see definition there until you have next to no fat left on your body. It's the last place fat will disappear from. No matter how much muscle you put there, you can't control the rate at which fat burns off. Nor can you spot burn.
Welp, technically you should be working out 7 days a week...wether its weights, resistance or cardio...(increasing your breathing rate for 30minutes a day is oh so important, even if its just walking.) ...buuut 1 day a week rest is all you need, as long as your not doing some sort of physically taxing job,...like a squash or football player you don't really need anymore than 1 day rest...i personally like to do 60 pushups when I wake up, and 20 every time I do up and downstairs in my house lol
if you work out every day then you just switch what muscles your working on. Like upper body one day then lower the next. That way you give yourself time to recover while still working out. Situps pushups and running are the only workouts you should do day after day
It depends on the workout really. If you are only focusing on the one groups (say abs) then it is best to do it every other day or so. This will allow the muscle group to recover. If you are going for overall fitness though, then change things up. Work on arms one day, then legs the next, cardio the following day then back to arms.
Plus there is a difference between toned and actually bulking up. If you are trying to bulk up then short sets of heavy weights are preferred over lots of reps with a lighter weight (for getting toned).
Personally, I'd say that 4-5 days of working out is plenty (one session per day). The way you're describing leaves absolutely no recovery time for your body. As for the "lower abs" that's just body fat (or water retention). in actuality there is no such thing as "lower abs". If you worked out less, you may actually see them.
You have the right idea about letting your muscles heal. The best thing to do is just alternate. Mon, Wed, Fri do a certain group of muscles and then Tues, Thurs, Sat do the other set you didn't do. Your stomach muscles heal very fast you can actually work on them every day. Google is also your best friend to get some nice workout routines.
Working out every day is the solid choice, it just depends on how intense of a workout you do. You can vary it every day, but the key of success is to maintain consistency and commitment every day.
Also note that you're going to feel the worst part of the recovery phase way after the actual workout. So keep that in mind when you're thinking "I don't feel that sore / fatigued at all, maybe another few sets and I'll be done".
The ACSM usually suggests cardio activity every day, for at least 30-40 min per day. As far as resistance training, that should be spread out to non consecutive days of the week, which allows for a day of rest in between. So maybe 3 days of the week you do endurance and cardio, then the off days, just do some easy cardio on a bike or swim.
I'm in the process of doing that. I only do 1-2x a week due to DOMS (delayed onset muscle soreness) you know that pain you get the days after a workout?
You build muscle on your recovery days. If you have DOMS you're still recovering. No point beating a dead horse.
I, personally, am just working out on my glutes and I found doing 8 different workouts (2 for each exercise day) really helps me to continue to shock my muscles so I continue getting DOMS. I'm seeing progress which is exciting.