I just completed my first 1/2 Ironman last weekend. If you're motivated enough to do the proper training for it, then you will definitely be able to finish the race. I would'nt recommend signing up for an Ironman before having raced a 1/2 or even an Olympic. The Olympic may be the way to go--see how you like it, then go register for the 1/2. As far as weakness goes--I'm 48 years old and weigh 110 lbs.--it's all in the training and definitely zeroing in on your weakness and working on it. But also be prepared for race day and the fickleness of the weather which can always throw you for a loop. My strength--running--was my undoing in this race--it was 89 degrees with humidity and no shade on the run from mile 2 to mile 12--but I finished, and I know that you can do it if you're motivated--it's fun! Good luck!!