if you have been working out alot for a long time the best thing to do is take a week or two off to let your muscles rest. I have found that adding more excersizes to my routine will help a particular muscle group. For example, Ill decide to concentrate on my triceps and add about 3 tricep excersizes to my routine. After about 2 weeks or so Ill switch to a different muscle group. I have a core group of excersizes that I always do to keep everything in shape. I happen to be a long distance runner, so long runs are the only thing I do for my lower body. For running/biking it helps to do it with a group of people. If you have a running/biking specialty shop I would ask there if a local group exists. You might be surprised how many saturday morning 5k runs there are if you live in a decent sized community (couple 100k people).

Giving advice about weight training could be almost endless. I would suggest getting a buddy to help you who knows what they are doing. This will make it more fun and is alot cheaper than a personal trainer. I have found if you make friends with other lifters they will give you alot of pointers in the weight room. Most will correct you if they see you do something wrong.