Here to help, so here it goes…

Monday: 3-5 mile jog.
Tuesday: Upper body work – Weights, push ups, arm endurance.
Wednesday: Half mile swim, build to mile. (64 Lengths of 25M Pool = 1 mile)
Thursday: Rest
Friday: Legs, core/abs – Dips(Squats), crunches, leg lifts, Flexability, endurance etc..
Saturday: Sprints – 30m sprint – 60m Jog, repeat about 10-12 times and build to 16.
Sunday: Rest

Work on building all your attributes and research exercises online.. don’t expect to build muscle from press ups or dips etc.. Research online.

Follow the program for 6-8 weeks before starting classes, learn more about boxing and purchase equipment if you wish.

Once you join.. talk to your trainer about how you can improve your boxing and fitness,
A boxer typically trains on:
Muscle Fibers – Repetitive actions such as straight punches for round after round.
Power Training – Throwing huge shots on the bag, Jumping up steps, Fast weight training.. All in short bursts with little oxygen.
Endurance – Banging out press up to burpee to sprints.. Teaching their bodies to keep going, going, going!
Fitness – Training in short bursts, having time to recover as best as possible and go again, e.g Sprints.
Conditioning – Taking shots/medicine balls to the body and preparing your body for punishment.
Co-ordination – Skipping and footwork, even when your knackered they gotta bang it out.
Cardio – Plenty of it, running and swimming and more.. Improving your heart and body efficiency.
Over conditioning – Training 13 rounds before a 12 round fight, punching with weights and survival sparing..

It is hard going in a class… Join and train with a friend.. this will give you a bit of a competitive edge and raise your confidence.
References :
Best of luck, let me know how it goes;D!
Boxing, Kickboxing, Health&Fitness&Diet.